Ah, curious... Sellmyretro still sells the Enterprise membrane? good news. It also has good quality, I have used both, the English and the Hungarian. The first more expensive, but the second farer from you(and me), so you pay more shipping.
The EDGE connector used is the 2,54mm pitch type, like on Spectrum and Amstrad.
Yes, Retrocables makes the cables one by one on demand. Order them the cables on their web page, never on Ebay....
