[woodcote]

Thanks Leo. Because the the car is in the fully-isolated loop (under direct control from the driver station rather than via the relay switch), it is completely unaffected by the polarity change. 

Isolating the entire loop and powering it independently was one of my tweaks to the ‘traditional’ method that Henk linked to and it solves several issues - a much shorter dead strip and no chance of the car ‘beating’ the polarity switch. Both those would give more than a stutter and risk a stall. If I could fit a slightly softer spring on the flippers, it would be near perfect...

Apart from a couple of low speed stalls on the upper loop flipper, the only issue is remembering to use the manual button to cycle through a couple of changes when I initially power up the system - otherwise the first change doesn’t work.