Re: Merc 650 lower unit repair (newbie)
I had a similer problem and it baffled me for awhile until I did some sectioned trouble-shooting. The lower unit shifted fine by hand, the cable on the shifter was adjusted fine, but wouldn't go completely in reverse so I eliminated those two which put the problem in-between. I figured the only thing left was the coupler and sure enough, it had worn splines. I replaced it and everything works like new...