A Wide Frame Chassis Manual is a must to work on a PTO clutch. You can find a manual in the Techincal Section on this site:
http://www.onlycubcadets.net/forum/showthread.php?t=232
Look at page 2-76B to find infomation.
There are 2 set screws in each hole on the PTO clutch. You need to remove 6 set screws from the pto clutch.