Fender Amp tech question, Please help if you can...

[SoulToStrings]

I own a Fender Twin reissue 2x12 amp w/ jbl upgrade speakers. It's worked great for several years, but recently I have discovered a problem. I'd really appreciate some advice or reasoning for the following problem.

The tremolo knob is no longer functioning. The tremolo sound is not coming out anymore , which I suppose could mean it needs new tubes correct?

But here's the weird part. The reverb still works fine, but the Tremolo knob no longer goes all the way up or down. It stops at a certain point and wont turn anymore. It looks like the knob got messed up somehow in it's turning radius. It's still attached the same way it always has been though, it's not damaged or anything. Any advice on this? Reasons why the trem. isnt working, or the knob isnt turning?
Help, I'm not too technical at all with amps & functions. Thanks
Brad

[Blue Strat]

Maybe the trem pot got damaged or maybe the knob isn't properly centered on the pot shaft. Look for a little "set screw" on the knob. If there is one, loosen it with a small screwdriver, remove, and reinstall the knob.

Note that your trem footswitch has to be installed and engaged for tremolo to work.

[SoulToStrings]

It appears that the knobs for the tremolo will go almost fully clockwise, meaning I can turn it past the 0 and 10 spots. I am assuming it is damaged. When I return I'm going to try unscrewing, and putting them on again and see what happens. Also certain turns of the knob makes the amp volume go up and down...weird. SOmething funky is going on with the 2 trem knobs of this amp. Any advice?
If this does not work, then the knobs are damaged I guess. I cant figure how this would have happened without me even playing the amp. Is it repairable at all? Fill me in on this
What should I try or do next? Thanks for your help
Brad

[brad347]

anything on a fender amp is repairable. It's probably just a matter of replacing the pot which sounds like it got damaged from over-rotation or impact.

Other things to check after that: Tremolo oscillator tube (last one before phase inverter) and trem optoisolator "roach."