What is it with "amp repair" guys?

[MarshallJMP]

Other amp makers also use quite high voltages, it's not just peavy.

[rnolan]

Hey RG, frustrating when you can't get a tech interested in helping  :facepalm: .  My tech has given up on my MP-1s, but they are much more complicated than a power amp, particularly as they combine digital switching etc. with the analogue audio circuit. 

The main things that come to mind for an older power amp is: 
Tubes (obviously) and the higher plate voltage may wear them out a bit faster.  And as you say new tubes will need to be biased properly. 
Electrolytic capacitors from that era, the liquid inside them hardens over time (whether they are used or not, it just hardens) and they get noisy, hence the foundation of the noise mods in the preamps, the mods are predominantly changing out old electrolytic caps.  For a power amp, the power supply caps often need changing to fix hum and noise issues. 
Pots and connectors, generally a good clean, de-ox etc. or replace if they are badly worn from use

[Harley Hexxe]

Gerry,

     Can you take a snap shot of the front panel?

     I believe I posted pics of both of mine a few years ago when I scored them. Take a look at those if they are still around and see if it's the same as yours. Mine are both 1987 models

[rabidgerry]

I don't have access to it right now but it's exactly the same as this one

https://en.audiofanzine.com/guitar-power-amplifier/peavey/classic-series-classic-50-50/user_reviews/r.99792.html

[Dante]

Sorry you're dealing with that Gerry...I feel your pain

Long story short: I finally did get my H&K combo back. It's pretty reliable, sounds great, not too heavy, but it's big. It'll do

Similar story about older stuff getting 'serviced'; I bought an old motorcycle a few months ago (1980 Yamaha XS850 Special) to give me a 'project'....well, I built a cafe racer out of it and then needed to replace the old carburetors. Nobody in town would touch it. The bike is too old to find parts for (that was the excuse)...but I'm asking them to install BRAND NEW Mikuni carbs...not old ones...plenty of parts for those....LONG STORY SHORT: I'm wrestling my carbs, rejetting, tuning, etc.  :hair-out:

[MarshallJMP]

Hey Dante, what's a "cafe racer"?

[Dante]

I split the Cafe Racer discussion into it's own thread, which you can find by using this link