What I found was a needle thrust bearing and a set of washers that are a perfect fit and appear to have solved the problem. This bearing allows you to *almost* tighten the shellplate bolt all the way and still allow the shellplate to turn freely. As a result, it takes all the play out of the shellplate and instead of the ball snapping the plate to the next index, it actually "glides" to that index.
The parts are local if in Atlanta, or if not, they are easily available via the web. If you order one day, they usually arrive the next.
So here's the fix.
Go to www.mcmaster.com (McMaster Carr - an awesome, just about has everything, parts supplier, that doesn't have a minimum order!), and get these parts.
5909K31 1 Each Steel Needle-roller Thrust Bearing Cage Assembly For 1/2" Shaft Diameter, 15/16" Od
5909K44 2 Each .032" Thick Washer For 1/2" Shaft Diameter Steel Needle-roller Thrust Bearing
That's PARTNUMBER, QTY, DESC
Mind you this is an open bearing so you'll need to make sure and keep it clean and lubed, but it should work.
Now, where did I borrow this... well Uniquetek makes a roller bearing mod for the 550 and while it requires a new "star" for it to work with this bearing, I figured, hey, there's no star used with the 650, so this should work and work it appears it does nicely.
I've made no other mods and will keep you posted as to my results... but *I'm tired of getting powder* all over occasionally.
Adjustment seems to be tighten the bolt to the stop finger tight, and then just a very small *smidge* back, then lock the allen screw.
IMAGES ADDED Below
Edited by Alan Adamson, 11 June 2009 - 04:52 PM.