Got a 55lb 48" MK with US2/AP. For some reason from time to time the depth finder (HMBD 717) goes crazy and there is a ticking sound from the top of the MK while using the AP. The depth readings and screen don't show correctly. It sometimes is when I change speeds in the wind or then sometimes when running the same speeds for long periods of time. Slowing down seems to correct it but some times not. Ideas please? Thanks.