I have a 48" mower deck that the PTO is not turning. I was able to help it start last week by turning the shaft and it built up momentum and worked normally, but this week, not so fortunate. I had previously put grease in all pulleys, and the gear box does have oil. I can turn the drive shaft by hand but the PTO won't take over now. when I drop the deck, the PTO spins fast enough to dig for oil, so I'm pretty sure my problem is in my deck. Any ideas on order of trouble shooting/repair? Thanks.