Sometimes after manufacturing the plastic hole will "settle" to be a bit snug. Just take a 1/8" drill bit and run it through the hole carefully. Watch this YouTube video -- click here. Once complete, it will be the perfect size for the shaft.
This is an easy fix 99.9% of the time. Watch this YouTube video -- click here. If this does not fix your problem, contact us and we will send you a replacement part if under warranty. Please make sure you are following the instructions in the maintenance sheet that came with your product.