After rebuilding coils a number of times, the rubber or silicone insulator starts to break down. One of the companies that FT buys coils from would surely be willing to supply this part on it's own. Sell it in 5 or 10 or 50 packs. They have been on fleabay for almost a year from a seller in the US, so I'm sure being next door to the factories you could get them. Thanks FT!