Hi Geoff my knowledge on these is zero apart from starting the old Lister up when we lived on the dairy farm in Gippsland when I was young. Is there anywhere you can get a squirt of starter fluid into it, that often gives things a wake up call, not sure what it does, maybe the initial explosion from the fluid settles the rings, not sure but it often works. At least it might give you an indication if the problem is fuel or not.
