Removed left rear wheel to repair leak. Removed grass from undercarriage. Replaced wheel. Tractor will not move under its own power. With engine off, I can freely push tractor even with brake on and in gear. Since the L100 is not an automatic, manual says it does not have a free wheeling switch. Did I hit a switch somewhere while cleaning? What else may be causing the inability to move when running and to be freewheeled when engine off and in gear with brake on?

Thanks.

There is a slot in the wheel and a matching sot in the axle that the wheel slids onto. You should have a small square piece of metal that slides into those slots when the wheel is one that engages one to the other.