FWIW, I got it working this afternoon. I tried driving it real slow both forward and reverse but no luck, so I took a chance and held the knob in while I sloooowly moved forward at about 1 mph. I watched the wheel gradually creep up to 9 and 9/10 and then finally, 0 and beyond. It's been working normally for the rest of the day. I still want to take it apart and effect a permanent repair, if possible. Any tips would be appreciated.