I got some delrin bar stock and whipped up two parts, one the size of the large bearing and one to replace the thin flat bearing. then i tossed that pesky nylock in the trash and made a round SS "nut" i slotted the "nut" after drilling and tapping a hole to make it a "lock nut" so i tighten it down to get the drag that i want and take up some of the slop, then tighten down the pinch bolt and it NEVER moves! I was so sick of the umi bearings i had to do something, and i was sick of having to adjust the nylock all the time too!
i have a shortened blowsion turn plate right now, im working on putting my ski back together, this time with an x metal plate and straight bars. it should work great with the bushings i already have.
of course, this may not help you, unless you have a lathe at your disposal...