I just did some more testing and now see I'm only getting about 20% max output in all modes - even built-in RTTY, FM, and when tuning. I'll try it on a dummy load (as soon as I track one down), but barring a miracle, it seems to be an issue with the finals or something else internal.
Thank you all for your help.
I looked at the manual for the PRO II and see nothing that indicates this is normal behavior, unless the meter in yours is wired wrong (or the switch isn't working) or you have too much gain someplace earlier.
It is probably NOT a final amplifier problem, because to the ALC system the final is just one more stange in the chain. I think some pro's had stability issues in an early stage, and certainly a stage oscillating could cause abnormal ALC.
If someone closeby had an identical rig, I would just swap it into my setup.
ALC works because the radio's POWER limit control is set lower than the detector's output voltage. The only things that can generate ALC is when the **gain** and signal level of the entire system ahead of the RF output detector tries to exceed the power level setting of the radio's power limit control, or SWR. Since the ALC is dependent on the entire system from audio source level to power control setting, it is tough to get a single cause.
A spurious signal could trigger it, or too much gain/drive, SWR, or an excessively low radio power limit setting. The entire system is equally involved.