I've always been intrigued by the sensors Lionel used on their old RailSounds locomotives to change the chuff rate or diesel RPM in the early 90's.
Though, I recently tried to rewire one of the hall effect sensors to a replacement board. This board had green, blue and yellow wires in that order from left to right. The old sensor had black, white and red wires from left to right (at least how they attached to the board). You'd think that just making sure the wires were going back to the right spots, everything would be fine.
Unfortunately, I didn't get any chuffing spinning the magnet-equipped wheel after rewiring. I don't know if there are any acceptable replacement sesnors or brackets out there, or if Lionel even carries them, but I think this is the last thing I need to fix (aside from a new amp) on one of my upgrades.