A 1992 +8 will have a LT77 gearbox.

These are prone to linkage problems , most of which can be sorted by taking the transmission tunnel off and getting at the linkages on top of the box, you probably don't need to take the engine and transmission out.

There is some information here https://www.gomog.com/allmorgan/remoteissues.html

Hope it is a straightforward job for you .