amp clipping earlier than usual?

You can visually inspect for bulges, leaks, test for esr and traces of 60 HZ downstream
or just get on with the business of it...
remember the voltages you are playing with can be fatal
get help versus poking around with a fork....

Sounds like a trip to an electronics shop is in the future for both amps, if not for anything more than an inspection and tuneup.

Have the amp checked out before blowing money on caps and such. It could be as simple as the bias in the amp being off (too high or low). 

I have some limited skill in electronics, mostly with good direction. I can replace the caps no problem. I have LTP transistors on the way anyway. Offset is a bit high for my liking so I will take care of both issues at the same time. It's just that I would rather not change the big caps unless I'm sure they're the culprit.

Ralph- yeah, more like 3db, noticeable. But if there's no distortion, and not a blown output(maybe yes?), what could cause that? My main concern is the transformer.

The fact that the power transformer is running warmer is a bad sign and I agree with others that the filter capacitors in the power supplies are suspect (and cause this sort of thing) especially given the age. If left unchecked it could lead to transformer failure.

It is also a good idea to check the bias points. This is not particularly hard to do; with the cover off a tech can do it easily in five minutes.

So there are the two things that really should be sorted and it could well mean that they sort out the problem too. But even if they don't this sort of service would be prudent.