I recently changed my lower unit oil on my mercruizer alpha 1 outdrive. After some internet reading I realized I did it wrong. I filled from the bottom hole untill oil came through my vent hole no problem. I replaced both plugs and then filled the resevor tank in my engine compartment last. After reading I found out that could cause a air pocket inside your drive. Before reading I started my boat trailered on the dock with it running in gear, I could faintly hear a knocking noise from my lower unit. I pulled the boat and took out the vent plug, lower unit oil spit out under pressure. I am wondering if anyone has any knowledge on this subject I hope I did not damage my lower unit and the fix will be simply changing the lower unit oil correctly. Please Help!!!!