Fender twin reverb 1966 vibrato channel Help please!

[IsraelB]

Hello, i need some help please!

Yesterday i was playing my 1966 blackface when i realize that the vibrato channel start sounding very thin in bass, mids and everytging, like i were using the bridge pickup of my stratocaster(i was using the neck one). Then i plug the cable into the normal channel and everything was ok. I already put new power and preamp tubes so i know tubes are not the problem.
Does anybody knows what could be the problem? Thanks

[IsraelB]

Also when the amp start to sound thin i realize the bass and middle knob does not work! till it fix alone and then both knobs start to work again.

[noworrybeefcurry]

try checking for cold solder joints along the tone controls. that may be part of the reason the controls arent working as well.

[IsraelB]

Today i am going to check that because when signal turns thin i realize that bass and middle knobs are not working!

Thank you!