* Delete 1 Part 70026 Light Gray Electric, Train 12V Remote Control Switch Motor 4 x 8 x 1 2/3 (Undetermined Type)
* Add 1 Part 70026b Light Gray Electric, Train 12V Remote Control Switch Motor 4 x 8 x 1 2/3 with Deep Middle Hole
Comments from Submitter:
70026a was produced until the end of 1980.
70026b was produced since early 1981 until the end of 1990.
These were verified based on the production dates that were engraved underneath these parts.
This set is from 1981 and so far, I have not seen any used or new copy coming with connectors without middle pin and with a "12V Remote Control Switch" 70026a (that should be from late 1981).
So the best thing is to not add 70026a and connectors without central pin (they would almost certainly be included together) until evidence surfaces.