Thanks for your quick replies, and sorry I havn't been able to respond earlier!
Decompressor works fine, also tried removing it and filling the hole with a spare spark plug - no result, although of course a bit harder to pull the starter. As far as I could see, the muffler/port is ok (BTW is there a trick to make the top clip refit easy, i found it a real pain...). Havn't checked the seal under the starter yet, was holding off on even more disassembly to see if there was some kind of magic bullet cure beforehand!
Bruce, the baseplate is still in place and no evidence around the nut to indicate it has ever been removed. No play side-to-side nor up and down. Thanks for the tip not to use Aerostart (it was one spray in desperation!) - is that because of the lack of oil to lubricate the cylinder or does the esther eat into the seals?
Thanks again, Dean.
