My 1959 JD830 (electric start) has started leaking engine oil in to the transmission. Doesn't leak when just sitting (eng not running). But when running, will loose about 1 quart per hour of running in to the trans. I understand there is a PTO shaft seal on the timing gear side that could cause enging oil to leak in to the transmission. I also understand it could be the seals on the crankshaft on the belt pully side causing engin oil to flow in to the 1st reduction gear case and in to transmission. My question is- does anyone know which side is most likely to be the problem. Both of these are going to be quite labor intensive to get at- so I want to start on the side that is most likely to be the problem. Does the fact that it only leaks when engine is running mean that one of these is more likely? Appreciate any help I could get. Thanks! Jeff.