[Bazzer]

"The reason I was reading/skimming the manual was to find out why there are 4 sockets for expansion modules but only 3 connectors for the track connection cables - not found an answer yet."

I only noticed this after you mentioned it as my focus has been on the zener diode issue with one of the towers.

Maybe Scalextric had aspirations for further expansion through that forth port, clearly at that time they were thinking Big !!

I wonder if Adrian has any insight on this ?

Baz