If yours moved freely then I would have concern as well. I've never had one that moved with little effort. I've wondered about drilling out the plastic on both parts and melting some and replacing it before, but I never have. The last 70 challenger I worked on had the pin broken or beat down so much that the coupler came apart in my hand trying to install the snap ring that holds the upper bearing in place. I just replace the shaft with one that was not beat up on both ends.