Spider III Preset Knob Issue

[erobinson710]

Hello I'm not sure if this is the correct place for this since this is the Spider IV section of the forum but I didn't see one for the III so i figured I'd give it a shot here.  Anyway, I've owned this amp for about 5 or 6 years now and I've loved it.  It's really been great.  Recently the preset knob (choosing like blues or metal or insane) has been having a very strange issue.  Basically it will sometimes randomly flicker between two different presets.  If I fiddle with the knob a bit it will eventually rest but it seems like it is somehow detecting it in different locations like its almost miscalibrated.  If i go all the way to the counter clockwise direction it doesn't register the last preset style and will only give me the "green" clean preset not the red one.  If I mess with it a bit it will briefly show up as the red one and then go back.  The major issue I'm having though is that I'll be playing using one of the channels that I have previously set up to the way I want it and the preset knob will freak out and do its thing which makes me use the preset instead of my channel which is extremely annoying when trying to jam out because it screws up everything.  I was wondering if this could be fixed very simply or if I"ll have to replace the knob somehow.  I've already tried a factory reset and that didn't work.