Chris said the upper gear stack went, who knows the cause. I always do my regular service on the boat. Chris did say that when they do a drive service, they not only change the gear lube and check all the seals, but also inspect the old lube for any metal, a sign that you may be losing a tooth or something. I don't know if all shops do this, but I'll definitely be have Prestige do all my service from now on.