Mica and others have written about how problems with intermittent signal loss or excessive noise with the F-1X can often be cured by "exercising" the input and effects send/return jacks.  By "exercise," we mean fighting corrosion in the jacks by plugging and unplugging a 1/4" plug in each jack 20 or 30 times every once and awhile.

I am a convert!  Yesterday, I changed the power strip in my F-1X/SF-2 rig (which required unplugging the Superfilter from the effects send and returns on the F-1X).  After I hooked everything back together I noticed a persistent high-pitched whine (right around 600 Hz) that wasn't affected by adjusting any of the gain knobs on either the preamp or Superfilter.  When I took the Superfilter completely out of the circuit and used the F-1X by itself it was (as always) dead quiet.  So, I figured something had gone wonky in the Superfilter.  To be sure, I then took the F-1X out of the circuit and went bass- Superfilter- power amp - and, again, the rig was dead quiet.

I said a bad word (actually, two), indicating confusion.  Then, light bulb!  I remembered the jack exercise procedure and figured I would give it a try.  After 25 plug/unplug cycles in the effects send and return jacks on the F-1X: voila!  Everything was dead quiet once again.

Exercise is good!

You can read about the jack exercise procedure in the F-1X FAQ here:  http://club.alembicguitars.net/index.php?topic=243.0

Love it when there is a simple solution to a problem!

And love it when the problem is simply solved.

That has been my saviour a few times too. Both in my bass and the send and return sockets on my F1-x. I have a rack which doesn't get used as my main bass head these days but certainly before gigging with it if it's been a good while I do that exercise process on all the used jack sockets just to be sure.