Hello Night Wizards,
My happiness from purchasing "excellent condition" EM-11 on eBay wasn't for long... First night out, and I hear loud knocking sounds when the mount is tracking at some positions. When using RA buttons at slow slew, I can hear awful squeaking noise resonating throughout the mount. Whenever the mount knocks, the star jerks in the eyepiece. The seller refused the refund, so I now have this project on hands.
Disassembled the mount, everything appears to be fine visually except the RA worm - when I turn it on its axis by hand in the carrier (see pic below) I can feel the motion is not smooth but jerky, as if there are "notches" in the bearings. Do you think I should try to replace both bearings? Could it be the worm axis itself is bent or it's less likely?
Any advice would be much appreciated. This is a hard lesson for me - never buy anything astronomical on eBay.