Regarding the rotor button....Seems OK on a resistance test but I'll see if I can source a replacement. If the suppressor fails a wire soldered between the contact in the centre & the tip would get you out of trouble.
The coil that was fitted when I got the FFR is a Bosch 9 220 061 100 which seems to be a non-resistor type to suit VW, Audi, BMW etc.
A spare motor came with a coil fitted and when the original failed I used this. It turns out to be a resistor type.
At the moment I'm still not sure what coil type to use because of the device inserted into the feed to the coil. maybe I'll just hitch up a meter and see if the voltage drops after a while.
Colin