Japanese Sega Saturn query - help wanted!

[Timbo Retro Hero]

I have recently restored a Series 1 Japanese Sega Saturn (grey body with blue oval buttons). I have put in a UK power supply and things appeared to be going OK. However, a previous owner has done the 'swap trick' thing and disconnected the wire that tells the Saturn whether the lid/door is open or closed. In fact, the disc spins all the time with door open or closed and this causes problems with some 'FMV heavy' games. Other games seem to be OK.

The wire that is loose inside the machine connects to the CD ROM but has been soldered together at the other end and I can't see where it should have originally connected to. The Series 1 machine doesn't have the internal 'switch' that Series 2 (round button) machines have that users tape to perform the swap trick.

Please, please, can someone give me an accurate description of how and where this wire connects to? (To avoid confusion, it's the two-wire/two-pin connector that joins the CD ROM that I'm talking about).

Many thanks!