Why is my peavey 5150 not as loud as usual?

I tried changing all the tubes and preamp tubes, and its still not as loud as usual.

I've heard of the bass nob getting disconnected and people having to resolder the wiring back together because if the bass is disconnected, then it takes away like half of the volume.

If you know anything on how to fix this, please let me know. ThanksWhy is my peavey 5150 not as loud as usual?
maybe next time you shouldn't get a god forsaken piece of **** peavey. if you can't afford something that expensive, at least go with an ibanez.