Hi,
Thanks for your mail. I did pull the glow plug and it did not glow,not because the plug was open but because the signal sensor is failing (In my opinion the rpm sensor might not be bad). Somehow it is not achieving the required signal to continue the process. Demagnetising the rpm sensor did help but not that much. Infact when I tried it this afternoon it first read 234 and then it did not achieve 200 at abt 5k rpm.
I also did as you mentioned, i.e. pressed RUN button after pressing the AIR start one but with negative result. It did not run.
Unfortunately I do not have the 500 motor but only have the original motor that came with it when I forst bought it. I presume it is the 300 motor. Would that be the Graupner 300 motor. I suppose the 500 motor will not fit in the 300 capsule. I suppose the whole front end would need to be replaced to go from 300 to 500...right?

Reuben