no it's not a fender, it's an orginal Ceriatone 

I've tested with new tubes, but that didn't help.  I got a tip to replace one of the electrolytes (i don't know if that's the correct english term...) I get my soldering iron and post here if it helps.

thanks anyway.

Hi, i'm a new guy at the forum.

I recently bought a used vibro champ and it sounds lovely, but the tremolo makes a loud squealing noise when i turn it on.  I can turn the noise off when using the foot switch, but i can get it back by turning the intensity back.  (when on full the squeal is gone, but passing twelve on the way down it comes on again)  My first guess is to change the tremolo tube, but if any of you guys have some suggestions on where i should start i would be very glad.

It is also a hum that i would like to get rid of, any suggestions on what to look on would be great.