Update: It turned out that the clutch plates were toast, so I had the transmission rebuilt. The plates were so worn that these adjustments didn’t help much.
Original post: I started to get slippage at a certain RPM, and the gear was difficult to get into forward. Sometimes it would not go into reverse even though I had pulled the shifter as far aft as possible. I’m trying some adjustments to see if it helps. The gears are much easier to engage now. There’s not much info online about this. Please comment if you have any other tips. The shaft continues to turn when in neutral.
Here’s a post with instructions on how to adjust the transmission:
It’s a Westerbeke 30 (Four-91) with a v drive

This screw and nut are not original. I found this out when I later fished the original bolt out of the bottom of the transmission.

Insides of the Paragon SA0V Gears





you are very intrepid ,The truth is out there .It may also be time to replace the clutch ?
Yes, that’s the likely next step.
Where can one purchase parts for a Paragon SAOV?
Hi Pete, contact Jim at Federal Marine http://www.federalmarinetransmissions.com