Small Engine Troubleshooting Problems? Ask a Mechanic Now.
F/R switch on the dash or at your knee? If on dash, the directional change is made at the controller. If large switch at your knee, the directional change is made at the switch.
The switch may not be making the internal contact for reverse. Swap the f/r cables on the switch ad see if you have reverse and loose forward. If you do, you need a new switch.
I see question is still open, did you find problem?