The tech at Redding Fuel Injection suggested the problem could be a stuck injector. Said to loosen the fuel line retainer caps on top of each injector, one at a time while running. If the noise stops, that injector is the culpret.On trying to start the engine I had to rebleed the fuel lines by loosining all the retainer caps at once and turning over the engine with the starter motor.
After retightning all the caps, I got lucky. The injector evidently cleared itself.Tractor is nine years old, 246 hours. I let it run for 10 Minuits or so and it sounds fine. Big relief. New injector said to cost $2600.00 ++
Cost to rebuild $600.00 plus labor to remove and replace, plus travel and or shipping. All's well that ends well.