Another Hobby Engine crawler crane.

[Supermario]

The problem might be the gear skipping and not the clutch. Try operating with the boom up more and keep the bucket closer to the machine.
If the problem is gone, it's skipping due to flex of upper structure.
Maybe drill a few small holes in the bucket side plates to drain the water easier? Not too big though or it won't be any good for dirt or sand!

Great idea fishing for golf balls

Mario