Machine spins over will not start unless you squirt it with ether after the machine is running runs fine all day.
Have you checked valve lash?
Does that unit have an air intake ribbon heater or glow plugs that are not working. Is it losing its prime of fuel. Putting air to the fuel tank with a blow gun and 1 PSI being held with a rag over filler hole will often cause a leak if anything is at all leaking on the voyage to the fuel injection pump. Does the unit spin over at fast enough speed, probably around 250 RPM, not sure on exact number. Is there sufficient fuel pressure while cranking. Then as Acecadet said are valves overdue for adjustment. Just some inexpensive tests before throwing parts at it. Simon C
By any chance do you have a loose air intake clamp or hole in the air intake and the engine is possibly sanded. Often times once restarted they tend to run not bad till either will not start it any more. Have you done an engine oil sample. It can point a person in the right direction often. Simon C
How many hours on the engine ?