I bought a second hand randall rg50tc for a great price yesterday, but the guy i bought it off said it needs new power tubes.

It kinda sounds not 2 good, i have a randall Rx120, and it sounds much better than the tube amp. The tube amp kinda has no bottom end at all, and when i play low strings, it just kinda sounds like brutal distortion not like propper distortion if u know what i mean, just a flat kinda buz style.

He said i should replace the power tubes, and looking at the tubes when i play it, one of them kinda glows but the others do not.

I dont know much about tube amps, Which tubes do i need to replace? The power tubes or all the tubes?

Also which power tubes will sound best? and whats the quality of the stock speaker like?
RG's & Mesa's