Wes,
I'm sorry you were disappointed in your purchase....as a fellow ham, I do feel for you.
As an Alpha owner (two 77Sx's --- one factory Sx and one "conversion" Sx....and an Alpha 78), perhaps I can add some clarity / context that might help?
I do NOT work for Alpha....just a happy customer!

And, I love Dick Byrd....a super good guy!

BTW, I do not know Tim (the seller), but I heard he has some health issues.
When buying any used amp, especially one that has been modified / converted, the buyer needs to do extra research / extra homework, and look closely at the pics...1) The linkage of vacuum-variable TUNE cap to the turns-counter dial is actually pretty heavy-duty....but, obviously this cannot safely be a direct connection....and, ironically, this heavy-dutiness can cause an issue in shipping / moving / loading-n-unloading an older amp, as it is ~ 40 years old, and if the vacuum-variable hold-down ring is no longer rigidly-tight, if you press hard on the turns-counting handle (like you would, if man-handling the amp in/out of a car, up/down stairs, into/out-of your shack, etc.), it will push back against the vacuum variable and then when you release your pressure the vacuum-variable will stay put (too far back) and extra space will now be opened-up in the mechanical linkage, and now you have slippage and/or no movement at all of the TUNE cap!
{which this alone could account for poor tuning and/or low-output!}This is a simple, and very easy-peasy "repair"....takes a Phillips screwdriver....but you do need to open up the RF Deck to access the vacuum-variable, loosen its mounting screw a TINY bit, push it forward against the turns-counter mechanical linkage, and tighten it down...close everything back up and you're good-to-go!
Lots of screws to deal with, to access the RF Deck, but other than that, it'll take you all of 30 seconds to do this "repair".
2) As for specifics of your amp, I'm fairly certain that Tim's two-holer 77 (like most out there) was a conversion. (some, like those that N4UQ did years ago, are so well done they're better than a factory 77Sx....but some can be mediocre)
I never saw Tim's, but assume you looked at internal pics, before making an offer? (but, perhaps there are somethings that you were not aware to look for....like the watt-meter board on the rear-panel / output connector, just above the vacuum T/R relay....whether it had 160m? whether any tank circuit changes / adjustments had been made? and, more importantly were there any pics of the load caps, to see if it had been overloaded/arc'ed if mis-tuned, especially mis-tuned on the low-bands?)
Also, please be aware that no matter what the lore (and the internet) says, while 77Sx is a 4kw amp, with an internal transformer, it is power-supply-limited!

That means, depending on the band and your AC Mains voltage, if you drive it with only a moderate amount (60 - 70w), it will run WICKED CLEAN (better than any transceiver connected to it, except for a pre-distortion-equipped ANAN or a MkV in Class A w/o any ALC)....and you can lay the "brick-on-the-key" with 3kw out (into a dummy load, of course)!
BTW, one of my 77Sx's (the conversion) was burned-in at the factory at 2kw carrier out for 24 hours straight, when the guy I bought it from sent it in to be cleaned/tested/adjusted before he put it on the market...I spoke with Gordon and Molly about this amp personally, and Molly confirmed 2kw out for 24hrs, and she mentioned that they did that with the factory Sx's too....that was over 20 years ago... (but I didn't buy 2nd Sx / my factory Sx, until last year, so that wasn't anything I cared about at the time).The reason I mention the above is that, depending on what band and depending on your AC Mains voltage (and depending a little bit on the exact internal transformer you have) if you drive a good 77Sx (conversion or factory) with 85 - 100 watts you can get ~ 4kw+ out, but your HV will be sagging, and this would be for SSB or CW, not "brick-on-the-key" RTTY (power-supply-limited)....and, some hams are "sold" on a 77Sx as a "5kw amp", which it can be with the outboard HV plate transformer, but NOT with the internal transformer!
{depending on what your expectations were, and on how your 77's conversion was done....this could also be a cause of lower than expected output...}And, while I've never driven it with more than ~ 90w, I have heard (and it does make sense) if you try to drive it harder (> 100 watts of drive) you'll be sagging the HV more, and the IMD worsens...although I was told that at ~ 5kw it's still better than most modern rigs and/or any SS amp....but, again understand that I've never done that, and never will! (I'm an IMD fanatic, you know!)
(yes, there are Youtube videos showing 5kw out from a 77Sx with the internal transformer, but this is ONLY for SSB rag-chewing service not 100% duty-cycle, and this is ONLY using a "special higher-voltage / lower-current" internal transformer....providing ~ 5000vdc...and this requires upgrades of the both the rectifier and HV filter cap, AND usually requires the user to buy two 3CPX1500 tubes, or take a big chance that they'll not flash-over a 8877....and, then after 1000's of $ all you get is a 5kw SSB rag-chew amp, rather than a "brick-on-the-key" amp!) Makes no sense to me, but some have done this.
3) And further specific to your amp, I assume it was a conversion from an older 77D not a 77Dx?
(not that big of a deal, but the Dx added 160m and I think there were some other minor tank circuit changes in the "x" models that permitted fairly seamless addition of a second 8877, as well as a few other minor changes?....and, I think this is where some lesser informed folks wish to say that adding a second 8877 screws-up the tank circuit, which is slightly true if converting an older 77D as you need to make those changes/upgrades, but not so true if converting a newer 77Dx...might be wrong here, it's been decades since I heard these details.) As was explained to me, while the 77D and 77Dx were both supposedly designed to have a second 8877....I was told that the D was not actually built specifically for a second tube as the Dx was. (not sure if that was fact, and/or that it applied to all D's and Dx's....but, it does make sense)
If this is the case, and/or with the TUNE cap linkage loose, etc. when you were trying to get "full output", it's possible that this caused some damage to the Load cap?
{and this, could also be a cause of lower than expected output}So, while it is a shame that you were not originally happy with your purchase, I think this may actually clear up some conversion confusion....
4) Upgrading / changing / moving the step-start relays and/or their fuses is not a "repair", it's an upgrade....(and, while I'd do it too, if I was doing other work/repairs, it's not a "repair")
Adding the watt meter board is also an important upgrade from a 77D....but, again, not really a "repair"...
Not sure why the transformer connector was "non-standard"? But, here again, this goes back to the type of "conversion" done, and could've been seen in internal pics, prior to purchase.
5) So, other than the minor "repairs" like the quick adjustment of the TUNE cap / turns-counter linkage and changing the transformer connector....the replacement of the loading cap, looks like the only real serious "repair" needed, the rest are additional upgrades that you unfortunately were not aware had not been done when the "conversion" was done....and, we (not anyone here, or even yourself) are not sure if the turns-counter / TUNE cap linkage looseness was the proximate cause of the load cap issue / lower than expected output issue.
Oh, and don't underestimate the TIME it takes to disassemble / reassemble the 77, as well as replace a few items...
And, I personally think Dick's labor rates are a bit low (damn, don't tell him I said that!)
So, while as I wrote up front I do feel for you....but...
But, you were buying a 40+ year old amp, that you knew had been modified / converted (and you sought it out for that reason), perhaps a bit more research on your part (and some care and inspection prior to powering it up)....and a bit more communication between the seller and yourself (like internal pics...lots of them)....would've eliminated most of these issues, and allowed both parties to be happy with the transaction?
So, taking into account all the above additional info / clarifications, I'd cautiously side with Tim (the seller)....unless he lied to you about something specific, to be a good gentleman and follow Good Amateur Practice, I'd say he might owe you a polite apology...(and maybe offer to pay 50% of the cost of Load Cap [$84/50], that's what I would do...).
I do hope I helped? (and say Hi to Dick from me....he's a wicked great guy!)
73,
John, KA4WJA