Digital Setting Circles for Discovery Problems

Hello,
I am installing a digital setting circle set on a Discovery 14 inch dob. I ordered the kit from Discover. I am having trouble with the bottom encoder. It seems (not sure) that the bolt it goes in slips when I turn the mount. I have tried tightening it, but when I do this it is so tight it is tough to turn the mount. Has anyone else installed these digital setting circles and encountered problems? Any advice would be welcomed. Thanks.
Jay

I like done a set with a 15" Split tube. IF they are the same then this bolt tends to loosen all the time. What I did was to use Lock-tite on the threads and then tighten it until the movement was proper but the bolt was firm. This has held now for quite a while without loosening. Before it would loosen with a few hours of use.
Floyd