I have added a new link for a pretty good video on how to maintain your tailstock quill to insure it works properly. The video is made by Ted Sokolowski who is a very good turner who produces a lot of very informative videos.
Ted covers use of the tailstock for drilling, and the attention that must be given to the tailstock to keep it clean and aligned.
Video is about 15 minutes long and worth the watch
Enjoy! Here is the link - Watch Caring for your tailstock
Kevin