David,
I took the switch out - it is made by ZhongXun and the closest I can find at their website is
http://www.zxgroup.com/en/productSho...&productid=203
The main difference is that the cut-out on the panel is 13.5 x 8.5 mm. A search on eBay found a few suppliers of KCD11 switches which are probably the equivalent - reasonably cheap, so could be worth the chance to see if they will fit. One supplier says the cut-out is 13 x 8 mm, the other gives the size of the switch itself as being 15 x 10 which is very similar to the existing switch I have.
Anyway, just thought I would let you know if you want to go down that road, If I do find a switch in my various parts collections that would work, I will certainly PM you.
-John
P.S. Maybe Skywatcher might have this as a spare part - could be worth a phone call to Bintel or Andrews.