I have an F1x that will suddenly lose the low end. Nothing but a real thin, high end sound comes out. After a short time, the low end comes back, but the sound will be very fuzzy for awhile. Then everything goes back to normal for awhile, and starts all over again. I don't know if the tube could be causing it or if it's something shorting out. Any ideas, help, whatever, will be greatly appreciated. Thanks

Rigorously exercise every jack on you f1-x, ins, outs, loops, and then do it again. There is a good chance that will end your problems. good luck.

Thanks!

Just concentrate on the effects return jack. There's a more detailed cleaning procedure described in the FAQ for the F-1X.

Thanks Mica, so far so good. I played a full night with no issues. It seems to have done the trick. Thanks again!