My DL4 has an odd issue, maybe someone has encountered this before and knows how to fix it. When I'm in looper mode randomly the 1/2 speed/reverse switch will activate. Might end up half speed, might end up reversed, might end up reversed and half speed, there doesn't seem to be a pattern too it, at least not one I can figure out. Any ideas? I bought it used a few years ago so warranty and a return are out the window.