I hope you are aware that the TS-60S was rated for 90 watts output,not 100. The TS-50 may have been a 100 watt rig.
YES good note there....90W 6M. I'm not going to get to concerned with the 80W I see now.
The panel meter must not be calibrated coz it reads 100W and the Bird reads around 80W. Nothing is wrong with my test setup/dummy.
Getting more into the problem, the RF power will not come up to the max every time. Sometimes, I key and there's a delay in the RF power going to the 80 W reading. I key several times and the power comes right up and sometimes a delay and then a lower power.
The slow rise in power or key-up delay shows itself better in FM mode or CW where that is supposed to be max power all the time.
So, maybe I won't fault the RF PA stage and look into the resistor packs and electrolytics.
No matter what I do mechanically to the radio, tapping, banging, or whatever, I cannot make the power drop off or increase.
What will make this harder to find is, if the problem is in the lower level stages on the TX-RX board. It gets pretty complicated in there.