I wanted to post here for the knowledge base. I had this same issue with my Variax 600 and it drove me nuts. I basically quit playing it because it would randomly switch to different models at unpredictable times and I didn't trust it anymore for live playing or recording. Figuring I couldn't make things worse, I recently took the electronics out, taped the entire inside of the metal "coffin" box with electrical tape (but cut for the vent holes), and sprayed the electrical connections (and model selector/switches) with deoxit and reseated them. I played it for about an hour afterwards and it seemed to fix the issue. If this doesn't work, I'm going to pick up a new PCB here: http://www.fullcompass.com/prod/210098-Line-6-50-04-0020