The rotary encoders are notorious for early failure. They're almost always the problem. I've had a couple repaired by Lexicon, but I've also had them sent them to me and installed them myself semi-successfully. (one screwup with overheating and destroying the pot). I've had 6 or 7 Vortexes and one last one in my rack that acts semi-weird and I'm really starting to become very of dealing with them. Gotta find something new for parallel stereo tweakage!