I have a 1965 Mercury 50 Hp outboard that I have replaced the impeller in. Went back together the first time perfectly but had some concerns that I had the impeller in correctly so pulled it back apart and forgot to put the shifter back in forward like the manual says. In the process of trying to get it back on the splines on the shift shaft and the auto lock cams (If thats what you call them) got moved or removed from the lower unit. I tried to reinstall and the shifter moves through all the settings but I only seem to have forward gear. I haven't put it in the water just running on the muffs on the trailer. When I pull it back apart how do I get all this lined back up so it will work properly? My manual doesn't say so I need some help please.