Hi Jim! guess you've seen allan 1066 videos @ fgw_in_fla post? Was toying w/ my rcbs 10-10 & noticed inconsistent readings when interchanging same powder charge. More than the 1/10th gr sensitivity gaurantee. I found that tapping on the base w/ a bp pen the scale indicator would come to perfect "zero" after a few taps. ??? I've long suspected the knife edge on the fulcrum which contacts the agate V-block to be causing the prob. Didn't want to mess w/ it lest I screw up the scale. Well, it needed fixin' anyway so I decided to polish the knife edges. Used a tiny Dremel felt polishing drum w/ a bit of metal polish. Much like you'd strop the edge of a knife blade. BINGO! No more problem & my 10-10 now matches my 505 for the 1st time ever...... Never considered the effect of movement of the counter wgt BB's in the pan support. I'll have to try that! BTW I didn't create a knife edge but left a little roundness so the beam could swing & find its own stopping point. (hope that makes sense) Dale