Here is some info that our old buddy Flip posted on this subject:
I usually have at least one mini ex or front loader in the yard to work on now. Once people around here realized I could repair buckets and get the smiles out of them, they started bringing them to me to fix.
Currently have a Komatsu excavator in the side yard that needs serious bucket work and the owner wants a hydraulic thumb added as well. If you are in a hurry, don't bring it here but if you aren't, I'm the guy. Hard to beat a mini ex for small dirtwork jobs. Much, much better than any tractor mounted backhoe. Been getting a pretty steady diet of front end loader buckets with smiles in them including some from my Kubota dealer. Just line bored and rebushed a brand new Kubota frame mount BH for him that came delivered with the dipperstick weldments welded in crooked so they could not install the pivot pin. Had to line bore it and turn a new bushing and press it in so they could assemble it and put it on a new Kubota a customer bought. Before the supply chain nonsense, they could have sent it back to Georgia and got a replacement but as it is, no replacements are available so I fixed the defective one. Customer will never know what I did after a nice coat of Kubota Orange 2 and I'm sure my dealer won't tell him either.
Interestingly, Kubota uses steel on steel pivots instead of the more common (in heavy duty) construction equipment, 660 CA bronze bushings with steel pivot pins which is why it's imperative to keep them greased regularly. With a bronze bushing, it's easy to replace an ovaled out piece. With steel on steel, not so easy, but then steel on steel is a heck of a lot cheaper to manufacture.
When I rebuilt my B670BH, all the pins had a little slop, but one in particular was worn more oversized- not egg-shaped, just loose. Between the worn hole, and the worn pin, it was a pretty sloppy fit. Maybe .060?
I line reamed the hole oversize, took it about .015 more to clean up the pin hole, then made a new pin that was about .045 larger than stock. Tite fit now. It should last longer than me, if it stays greased.