Aah. Answered at least the first part of my question. My focuser is similar to this one ...
https://www.youtube.com/watch?v=gpIt...ature=youtu.be
You essentially have to dismantle the whole thing. Of course, the instructions don't cover this scenario!!
Now, having taken the silver doodah off the end of the motor shaft, I'm faced with the job of trying to get it back on firmly. In fact, in the above video, the guy recommends not to take it off unless you need to use the alternate attachment as it's hard to get back on! Doh
