I am having problems with my Newtonian. It is a GSO 6" f6 OTA on a home made Dobsonian mount. With a Celestron zoom eyepiece I can't quite focus because the Crayford focuser bottoms out before it is in focus. A Teleview Plossl 25mm is barely (I think) in focus when the focuser bottoms out. I assume that the primary needs to move towards the secondary? Any suggestions appreciated.