If the 10mm headed bolt/set screws are spinning, it is no good forcing them up wards as you will bugger the bottom half of the stat housing as well as shagging the top half with it.
Personally I'd be taking the whole thing off to have a closer look at,,,,,,,if it is possible to fix then go for it. BUT by the sound of it you will be lucky enough to rescue the top half,,,,,,and you will be on the look out for a new or good second hand bottom half of the stat housing.....
Regards
Fritz,,,,,,,,,,,,
One day you will find me,,
Driving in my Camper,
With a Surf and Paisley wrap on both sides....
Take the assembly off ... very carefully cut the bolt head off ... now carefully push the brass insert out downwards and re-assemble using an M8 bolt instead of the M6 (10mm head) and nut you'll have to drill out the hole in the top part. If you're lucky you'll get away with it, although you may have to re-seal round the joint with silicone or similar.
Ian.
The Hulley's Bus 1989 2.1DJ Trampspotter LPG courtesy of Steve @ Gasure