I also have a 2544 also with PTO problems. I was mowing, 1 1/2 hrs, PTO just stopped. Fuse is fine, replaced anyway. Blades are clear. Checking everything I found a black wire, , looks like 18 ga. wrapped around the shaft on the engine side, sheared and frayed.
When I start the PTO, it sounds like it spins, but doesn't engage the belt-pulley. Try to spin by hand it locks so I guess the key isn't broken. No? I can't find where the wire goes, can't find a diagram on line showing the PTO with the wire, can't get it fixed - any ideas? I don't think it is just debris, but can't find other leads. Sure would appreciate anyone's help. Thanks, Sam