I've never had that problem with Win231 and Lee powder measure. Probably loaded close to 100lbs of it.
But, that is a frequent with larger flake powders particularly Clays, 700X, Unique, BlueDot,RedDot,GreenDot, ,,,,,,,,,,,, you get the picture.
You may have had some powder bridge under the disc between the Elastomer Wiper and the Disc. This will cause the problem you have described. I've had powder bridging with Titegroup due to "clumping" of the powder in the hopper.
Suggest you check the hopper and possible clean/degrease-dewax it by washing in dishwater detergent and letting it dry without rinseing or hand drying----- This will remove any grease and/or wax that can cause clumping or "static" cling to the measure surfaces.
Bullseye and Win231 have been amoung the most "reliable" powders I've used through these measures.
Be sure too, that the hopper is tightened snug with the measure base. BE Careful if using the small hoppers with the "wood screws" holding them to the base, they crack easily. I have converted all my disc measures to the larger hopper and use a nylon lok-tie straped over the bearing surface of the sleave where the pivot arm bears against it on the threaded release. This gives it a "plastic" bearing surface and also acts much as the "shim" procedure mentioned above, causing the expander to engage the case at a "shallower" insertion, increasing the range of adjustment after case mouth impingement. I also flare my cases more than some to ensure that the cases don't shave my lead bullets (approx. 95% of what I load for all pistol cartridges).
If using the "chain" return arm, I recommend you go to the closest Auto Parts store and get a "Throttle return spring" to attach to the powder measure. I've seen the other end connected to the mounting bolt/screw and others just hooked on a screw eye or just a bent nail driven into the bench and the end of the spring twisted around it. Stretch or shorten the spring to give adequate tension to return the powder measure to the "return" position positively. One friend used the spring off of a 69 Chevy Camaro he was restoring at the time- just a suggested starting point for a particular spring recommendation...................Worked for him, (and bent nail too!)
Also, check the spring tension if you're using the older measures with the spring on the actuator arms, I've had one that was/is weak. I like using it with some RIFLE carts. such as .22 Hornet and .32/20 that have thin case necks, so keep it on a separate powder measure for that use.
Hang in there, it only gets easier !!!!
Your "problems" are just part of the "Learning Curve"
