So, i'm messing around with the lower unit today on this old Merc 400. I've had this thing apart many times, and it's always a B**** getting it to go back together properly. It was in neutral when i pulled it off and i didn't touch anything. While putting it back together, things won't line up as usual. So i put it in reverse on the controls and on the motor, it slides back together no problem. Then, it won't shift out of reverse. So I don't force anything, take it apart again rotate the little cam on the shift shaft, goes together again, still won't shift. Take it apart again, now the shift shaft pulls out of the housing. I put it back in however, now it just spins freely and doesn't shift. Now i'm wondering is this thing completely broken? It doesn't look like it busted, but doesn't seem to want to work now. The housing is welded together near the prop so there is no getting this thing apart.
