Ok, thanks very much Jack and Grumpy all is well and things are purring like a kitten.
I had a great time pulling the drum apart and removing all of the ancient, rock hard grease, before cleaning and re-lubing as you recommended.
As a tip for other younger players
I honestly do think that it was the lower part of the drum clutch adjuster fouling the drum sprocket that prevented the unit from driving and jammed it from being able to be pulled backwards...so worth a look if anyone has the same symptoms.
Still like I said it was good fun, and really medically necessary to give the drum a birthday. I really enjoy working on these, always something new to discover, and such a well designed and produced machine!
