I have a 1976 Evinrude 200 Hp Outboard. Will not shift into reverse. Tried cable adjustments and not it. Tried manually shifting only grinds and **** level jumps in hand. Tried Lower unit removal for bind ups in shift arm, no it either. It Is a hyrdomatic lower unit? Any suggestions will be welcome as I am stumped and any shop manual I can find has no advice 