Pto turns when not under a load. As soon as you put it under a load, it makes a noise and stops turning. What's the problem and how hard a job is it to repair?
Guessing here, but it sounds like there is a clutch pack that is out of whack. Difficulty is probably from pretty easy to needing a rear split and total tear down. Not sure without a look at the manual. And i fer sure wouldn't tackle it without a manual!