2008 SANTE 230 - lost reverse

[quaylefarmer]

Boat has been running great.

Shifted to reverse coming into the dock tonight and it wasn't there.

Has forward but some slipping.

Makes a cyclical squeaking sound.

Checked fluids in trans and V-drive (both look ok).

Trans linkage looks to be in good working order.

Any suggestions before I go to the dealer?