It is always a good idea to contact customer service at
support@vexrobotics.com or 903-453-0802.
While John, Ricky and I check CD, our customer service department responds to customers who call and email. Every customer who contacts our support line directly is having their bad bearings replaced.
The issue that went undetected was that the hex was broached off center. Our standard bearing race runout test did not detect this failure mode. We have now set up a special hex runout test on every hex bearing.
The reason the bearings are out of stock is so we can replace all the bad bearings that have already been received by customers.
For extra information, only the 1/2" hex bearing is affected. The 3/8" hex bearing is not affected by the defect.
Paul