Saw would run fine for five minutes, then quit. Replaced spark plug. Saw ran fine a couple days ago for several hours of intermittent use. I fired it up yesterday and tore into some 16" logs, sustained flat-out running. Saw ran for about twenty minutes, then quit. It would pop after about seven pulls with the choke on. Opened the choke and started the saw, but it kills as soon as I open the throttle. I've cleaned the carb, put a diaphragm in. Seems to me that it must be sucking air around the crankshaft seal (seems to be revving a bit high.) Any other ideas of where air can get in? If it's the crank seal, how big a job is it? Can you pop the seal out after you get the clutch and whatever out of the way? I saw a download for a service manual for the 029/039, but couldn't get it tonight...site down for maintenance.