Close Brownbaker! However, it is only just a bit below your link. So yours will work. Here is what Laurie is looking for
https://www.gomog.com/allmorgan/seals.htm#R380 Laurie is in luck as I am currently coaching a new owner with an earlier Rover Plus 4, a 1994, in exactly these tasks. In that effort, I refreshed the old page, adding the draining and filling point and instructions for the R380s.
I swapped R380s into all my Plus 8s many years ago. They have a higher bhp/ torque capacity than the LT77s. The best game plan., IMHO.. Btw, I have never encountered an issue with any Morgan R380, except once.
When dear departed and deeply missed JHS2 took my CDN Plus 8 for a drive. 
But I guess R380s are now "old" gearboxes
albeit much stronger than later fare often turned to now. 1. Could be someone put in the wrong fluid (less serious than doing so with a LT77 but ...... ) So Laurie's game plan is correct at this stage. Changing the fluid IS the first thing. And that article gives better fluid suggestions than AI or google
which is often only giving US substitutes for products not made in that country.
It is making a mess of GoMoG advice 1000s of times daily as well. Can't figure out how to stop it. Ideas?
2. Laurie's.remote bushings are going..or gone as suggested.
You see the famous polyurethane versions, (UKC854POLY) are aftermarket and not original to Sd1 remotes, even after we all realized that the original rubber ones fell apart. It is the second thing I'd check using,
jbk's wisdom.
3. OR if it was a LT77 I would say the syncros into 2nd have seen better days. That was the fist gear to go.
4. The pre-February 1999 R380 have issues cured after that date and/or resolved with a rebuild kit. Dave Ashcroft, the world's undisputed repairer/parts-supplier of LT77s and R380s, speaks of such things here.https://ashcroft-transmissions.co.uk/technical-library/?technical_library_product=1261
Lorne
