Well I have two old style lee perfect powder measures. They both do well with stick powders but leak and bind with ball powders, with w296 being the worst I've tried. Been using them anyways and they are accurate.
Well after researching it and mulling it over a while I finally decided to lap the rotor and body.
I disassembled the rotor, cleaned it best I could with a rag, then smeared a layer of 320 lapping compound on the rotor. I put the rotor in the body and rotated it by hand back and forth, occasionally spinning it all the way, first one direction then the other. Probably bout a minute. Then I wiped the lapping compound off the parts, being sure to get what was in the nooks and crannies. I put my finger in my graphite power and gave both the body and rotor a coat.
I reassembled and run some 296 through it. Wow! Should have done it years ago. So smooth, no binding, no leaking.
Then I repeated on my other with the same results.
If you're considering lapping your PPM, don't wait!