gunrunnerjohn posted:IMPORTANT! The regulator triac MUST have the isolation from the chassis, if the plastic sholder washer and insulating pad is missing, you'll cook the new one!
The last one of these I got did not look like the Lionel replacement parts page image copied above. In particular, all the components were within the black shrink wrapping (no triac sticking up outside of it) and there were five wires instead of the four on the original part. The part I got looks exactly like the OP's replacement part and is really fairly small.
I still put some insulation between the shrink wrap and the frame and connected the four original wires leading to the old regulator to what I worked out were the corresponding outputs on the new one. I can't now remember exactly how I dealt with the fifth wire but GRJ's diagram above looks familiar. Anyway, it worked.
