Small Engine Troubleshooting Problems? Ask a Mechanic Now.
Welcome to JUST ANSWER small engines, let me try to help you !! I don't know it all, but maybe together we can get you a satisfactory answer!
I see nothing in the electrical system, other than the pto switch and the pto clutch. With it blowing the fuse, when you hold the switch, the electric clutch sees to be taking too many amps to work the electric clutch. Have you tested the clutch or replaced it? This looks to have an older style clutch, which has three springs and three self locking nuts, this allows the armature to be moved closer to the magnet. By closing the gap between the two part, may let it work easier. Other wise the electric clutch likley needs to be replaced.
Gap needs be .015 , but as long as it opens, and releases, you can't get it too close.
I see question is still open, did adjusting clutch help?
Diode? Have you jumped the clutch direct from the battery to be sure it works? Only diode I am aware of is for the charging system, and has nothing to do with pto clutch. and is NOT internal to engine, but external in the wiring coming from under the flywheel. I think clutch is pulling too many amps, and will have to be replaced.
I see question is still open. Did you find probelm? Does the clutch engage on direct voltage test?
I think the pto clutch will be the problem, please rate when are ready to close.