That's awesome!
My team was considering this but the only way we though we could disengage the drive motor from the pulley system was to use some sort of clutch...
boy did you prove us wrong!
But for the 6000$ question: are electromagnets Legal?
I hope they are, but from what I see your design could be modified to work without one (some sort of railing system with a latch perhaps).
Good luck!
-Leav