I have the following problem with my FM-4: One of the switches (the one I use the most) suddenly only works about one out of four stomps and also flicks over to other pre-sets when stomping. So when I stomp the particular switch another gets going instead. What to do? Thanks a lot!
Music - Line 6 - FM4 Filter Modeler Effects Guitar
Answers & Comments
First thing is to quit "stomping"... these switches are not made to hammer very hard. There are several possibilities here... make sure one is not carrying dirt that works its way into the area that pushes in as it can block the contacts... keep the shoes/feet clean. If the retaining nuts around these come loose and pressure is applied, the circuit board inside can be bent and or broken.
What you can try is to lube the switches with CRC226 available at Home Depot in the electrical depaartment... use ONLY that product as there are other CRC products there as well. Flow a liberal quanity down the plunger of the switches.and operate them. This might work if the contacts only need cleaning and lube... HOWEVER often abused switches have broken parts and it is fatal and requires replacement... The bad news is that MOST of these are Metric and the replacements you find at hardware stores may NOT quite fit... also they cost about $10 each typically...
The above are hints and insights for you... ultimately you will likely have to have the switches replaced and unless you are electronically adept, it will not be a DIY project.