Replacing the resistor is an easy job, the bad part is if you don't have an electronic component store like the old Radio Shacks around, You need to order them.
The factory resistor value is
5.1kΩ:
https://www.mouser.com/ProductDetail...TCrgCxtI5k8%3d
If You want a little more speed in Reverse than stock, then use a
3.9kΩ:
https://www.mouser.com/ProductDetail...bJbNcoVSYjQ%3d
I would check first to make sure the sonic weld is not what failed.
Follow the
black wire from micro-switch #3 back into the harness, You will find a resistor before it splices with the white wire.
Make sure that splice (sonic weld) is good.