Reverse sensor problem.

[yamaha3]

For some reason, my reverse light comes on only when transmission is in 5th gear with some pressure pushing forward. Reverse lights will not come on with transmission in reverse. Yes, lights are correctly hooked to the reverse sensor and NOT the 5th gear position sensor.

Are reverse sensors likely to go bad? Are then adjustable?

Have safety inspection coming up and can't figure out what is going on here.

Any hlepful hints would be appreciated.