I had similar problems when I first joined MARS (since withdrawn my association)....  Yaesu was more than cooperative with just an email of my emailed acceptance email notification from the state director....  they sent me the mods for my FT-897 & FT-2900 radios - NO PROBLEM.

But then I was considering another radio, i.e. the Flex-3000, but they wouldn't even reply to my requests.....  so I bought a ICOM-7410 radio instead (for less money) with mod info available...

BTW, my FT897 radio is modified (by me) and I found the public available internet info and pics better than what Yaesu sends out.

I am leaving my FT-897 mods in place for the time being, in case I elect to re-join at a later date,  but I am not modifying any other radios, since I have no need to access those freqs at this time.

I joined MARS in June, 2012 right after I got my General License, which was probably too soon (i.e. a mistake).  I had been active on 2m with analog and DStar, but had no HF radio or experience, no antennas, tuners, etc etc etc.   So it has taken me a little time to put all that together, except now my 6 month "/t" training status is up (I finished all my basic training reqs, except for air time).....  NTL, due to the delay in my HF expertise (& lack of gen HF exp & equip),  I withdrew my MARS membership, although I am still getting all the emails, etc.  I don't know if I have been officially removed or had my status changed to "leave of absence." - either is ok with me.  

The leadership here in Oklahoma was very nice and courteous,   but I did detect (I think) a little pressure on them to get an active group all wrapped and qualified....     During this process I noticed a new "m.o." being preaching from MARS leadership about being a comm support operation for not just the DOD branch, but to FEMA, local fire, police, etc,   which is probably a good thing, but it does overlap with many of the other ham emergency ops groups that are already plugged into the local emergency needs - maybe better plugged in....

In Oklahoma there are a lot of hams, but very few MARS volunteers, & I don't quite know why.    Seems MARS has a hard time recruiting people and maybe a hard time retaining them, & I have some thoughts, but nothing verifiable.

If I was retired I'd love to spend more time with my radios & with MARS.   However I am still employed, and still have many other commitements that get in the way of my hobby.....  so a lot of compromises take place, which does get in the way of doing MARS nets & such.....