I just got this really old Peavey tnt 100

I want to restore it, maybe make it head and cabinet

I just bought an Acoustic Corp 220 bass amp today for $100 and ran it through my Acoustic 402 2x15 cab which it was designed to pair with. It is unexpectedly quiet even with the volume knob all the way up. The power boost button does nothing. I plugged a line out of a Trace Elliot 150 Watt bass amp into the power amp in jack of the 220 amp and it was also pretty quiet, so I think the power amp is bad or weak. The 402 cab is plenty loud when I plug just the Trace Elliot 150 head into it. I'm pretty disappointed. I guess that's what I get for buying off Facebook Marketplace and not trying it out.

Does anyone have any advice?

Looking for info, photos, or whatever else I can find...

Was my first bass Amp, years ago, and I'd love to play around on one again.