Steve,
Thanks for the response!
I think this is still a 3 speed because its a Euro - I know USA and Japan got the 4 speed first.
OK, so solenoid out is not a big deal - screws out, retained how?Check for action with 12V, if not, replace? Also replace any O rings visible - I assume these are on the solenoid body somewhere? There are many MB parts shops over here (only 1 Porsche dealer, and 928 parts are rare), so I should try them for a solenoid? Any idea of part number - same as the 4 speed by any chance?
The cable seems pretty good - I took some slack out once and the shift points moved up quite high, so I slackened it off again.
Is it fair to say these boxes are fairly robust, considering the 928S is 300hp? I have seen a post suggesting the reverse band can be adjusted - cut a slot in the headless bolt, screw in to bottom, back out 3/4 turn - sound right?

Many thanks for your help.
John P
Riyadh