Thanks to you all. I will have to wait until later this week to try out these suggestions as I am now off island so don't have access to the tractor.
I've never taken apart the yoke of a PTO coupler. Are special tools required? Ring pliers?
Someone asked what brand PTO shaft. Not certain but it came with a Bush Hog Squealer cutter. I've never liked it because you need two hands to pull back the retainer ring from opposite sides while pushing it forward to couple with the shaft but it hasn't given me any other problem until now. I prefer the twist type that came with my Rhino finish mower.
I'll double check with Kioti before pulling but I like the idea of using a strap and the comealong to provide controlled force rather than the chain and tractor motion I was initially considering. I might look around for a prop puller too as that might be even more controlled and would not put any stress on the tractor PTO.
The PTO shaft was clean when I put the shaft on only 24hrs before this happened so rust and dirt is less likely the cause than jamming forward. I'd never had this issue before but I suppose the shaft is too long and I'll fix that. As Willl pointed out, the photo does seem to show that the retainer ball (only one ball is visible on my shaft
) does seem to have deformed the cup...though I've never looked at it closely enough before to know that is a change. Still, as others have pointed out there is almost an inch of shaft beyond the end of the retainer cup so maybe it isn't jammed on too badly.
Thanks again to everyone for your suggestions. I'll post when I have some follow up.