I have an OMC stern drive. When it is in the driveway with "earmuffs" on I have no problem going from ahead to astern or astern to ahead. However when the boat is in the water, it will not shift. It sounds like the gears are tryin to mesh but with no luck. Last year I spent over $900 tring to get it fixed. The mechanic said it is working now and proved it in the yard. But as soon as it hits the water it won't shift from astern to ahead. It gets embarassing driving around in reverse. Please help.