Hi Bob, thanks for the reply.
Yes I have the manual but obviously these are very old engines now and I understand fine tolerances have probably slightly shifted but it runs OK and I dont want to dive in too deep, I am a mechanic by trade but not familiar with these engines, I have a decent battery I use that I know is good, starter had been stripped and cleaned and engine has been rewired with a new alternator, glow plugs have also been checked and confirmed working, I did not see in the manual about 20 seconds of heat from the glow plugs, I will give that a go thank you.
I presumed the decompression lever just opens a port to allow the compressed fuel/air mixture to escape? How could this cause the piston to hit a valve?
Thanks again Bob