!964 Fordson Super Dexta PTO Problem

[fireman4074]

I am having trouble with my pto when I engage it for example bushhogging it will disengage on its own. It will stay engage until it get in some high grass unless i raise it up. If this is the problem, how do I adjust it. The tractor is a diesel 3 cylinder. I have tried to use a heavy spring to keep it in gear but now that wont work either. It will grind. I check the in/out play on the pto shaft. It is tight with no play. Is there a clutch that need adjusting. Have anyone had this problem and got it fix? IF so, is this a DIY job or shop fix?