I took a rear wheel off to fix a flat, hasn't been off for 6 years, so I tapped the wheel with a rubber mallet while turning it. I had the neutral switch pulled out. Of course I had to tap it back on, while turning it. Got the wheel back on pushed the neutral switch back in, got on to mow, doesn't move. Something has happened to the transaxle, probably from tapping wheel on and off. Any suggestions? could an internal key have dropped out? Are these powered gears, could I have broken something?