I found our Cruise Control Unit on the 310, right up under the dash above the steering wheel mount - what a stupid place to put it!
It is virtually impossible to get at, and a quick look at the manual says "adjust it......."?!
So my inoperable CC is definitely on the back burner so to speak. I am sure it is a fuse or something daft like that. It has never worked in my ownership, and the PO's didn’t say.
I just need to get at that GM fuse panel on the bulk head - reposition it, so I can see what is going on, THEN possibly sort out the CC. It looks to me that the power is one of those questionable "insert" plugs that push into a fuse holder. There is a vacuum there - somewhere - but I am not sure that is the problem.
Out of interest does anyone know if the vacuum gauges are repairable, mine constantly read the same - it never moves.