NS5B re attaching lower unit

Replaced the water pump impeller on my 1990 5hp Nissan 2 stroke and that went smoothly. When I went to re-attach the the lower unit, hooked up the gear linkage no problem and got the drive shaft inserted into the engine to the point where turning the prop turned the engine but still needs to go up another inch to bolt on? I've tried shifting the motor and turning the shaft I just see to be an inch too long??? None of the Youtube vids that I've been trying to self educate myself with seem to address this issue. Any ideas would be of great help.

First, always do a complete wp kit; not just the impeller. Lasts longer and pumps better.
You are not engaged correctly; you may have the water tube striking the wp housing. Drop it again, make sure everything is aligned, and reattach.