Mine started that way and just got worse. Now it vibrates every time after it locates a target and won't stop till I hit it or turn it off.....unacceptable
Throw it across the park. That's what I did and its worked fine ever since!
Have you put a spacer in the battery compartment to keep the battery snug?
I also put tape over all the openings and its worked fine ever since.
G2M