Hi Andre,
Please can you be more specific on the mount you have? Based upon the age I assume this is with the non-tucked motors and a Gemini 1. I have the tucked motors and a Gemini 2, so mine might be too different to advise from. No gear boxes?
Perhaps this video shows your type:
https://www.youtube.com/watch?v=kBi10ztreDw
If you are replacing the worm, you probably should replace the Oldham coupler and the worm bearings at the same time as these will have an effect too. The bearings you might be able to source locally, the Oldham coupler you might be need to get from Losmandy.
The worm and blocks will need to be adjusted to properly mate with the ring gear. I think this Losmandy video is a good guide:
?
Hope this info helps.
John
Note: The first video shows a GM8, which may be different than the 10 year old G11.
