How do pellets and pellet jazz cause the cup to lock up? Does this sound like a pellet quality issue?
It appears that the clearance on either side of the cup is evenly spaced, as it sits in the bottom of the pellet hopper. At this point, I'm calling it this:

It runs great for about 15 minutes and soon becomes clogged and locks up. Removing the restriction with a knife blade frees the cup.

Is the clearance of 1/8" on either side typical?
What are the recommended remedies?

The pellets are a year old, and were bought from a store whose name sounds a lot like Routhern Rates, but I'm just asking more than anything about pellet quality...