Hey, I just picked up a Sampletrak off of Craigslist and so far it seems like most of it works. However, not all of the pads work correctly. 5-8 seem to activate just fine, 2-4 you need to find the sweet spot, and often before you do it'll start to play the sample multiple times like rapid fire, and pad 1 doesn't respond at all; no sound or led light. Has anyone encountered this before? Could this be repaired? The whole machine doesn't appear to have been beaten on, just a little dusty on the knobs.