Hello guys bought a used boat, it's a 87 century, with a 3.8 omc, i/o, took it out went about 100ft half on the throttle, popped out of gear, engine revved, took it out of gear shut it off and towed it home. Still starts, we checked the linkage, the lever on the engine moves into gear but wont engage. We have it out of the water, removed the prop, started it with muffs, and the gear does not spin either direction. We have been hearing coupler or gearbox, any suggestions?