Can’t get reverse after lower unit installed

[Drrumbe01]

I’ve removed the lower unit of my AlphaOne I put the gear in forward locking down propeller and making sure spline falls in in forward. After installing. Checked shifting and handle won’t go to reverse. It does go into reverse while lower unit is not installed and it did before I removed it. I just wanted to adjust it because it was making a clunky noise in neutral. 94 Celebrity 4.3L

what is it that I need to do if it must be installed in forward?

 

[Bt Doctur]

Easiest to do off the boat and not just dropping the lower unit.
Shift the control box into full fwd. turn splined shift shaft of lower unit fully clockwise while turning the prop CCW il locked.THis is FWD gear in the lower unit. Raise lower unit aligning water inlet tube and turn prop CCW about an inch to line up the driveshaft splines.raise drive MAKING SURE THE BRASS UPPER SHAFT SLIDES ONTO THE SPLINED LOWER SHAFT FACING FWD ( in a straight line)
install front nut by a few threads, install side nuts and tighten MAKING SURE THE BRASS UPPER SHOE SLIDES ON THE LOWER SPLINED SHAFT
Install remaining hardware and fill with gear oil

 

[Maclin]

I had a problem with the shifting cable end (long rectangular block) that stays in the gimble housing being a little crooked, and the shift shaft linkage roller would want to not engage properly as the drive went on. I had to stop when almost in all the way and move the shift shaft roller to where it was engaging the cable end "fork". The pic below shows how the cable end (long rectangular block) wants to tilt at almost 45 degrees until it can go into the drive housing a ways and straighten up.