[Burf86]

I have only just gotten around to trying out the 4th axis that I bought with my machine in 2020 and it's throwing up alarms saying I need to check solenoids and stuff when I do the alignment.
This cable (pics attached) is unplugged in the cabinet around the back that I have turned a blind eye to as it hasn't caused me a problem until now.
The cable is numbered 2901 and it leads to the 4th axis. It is supposed to be plugged into the big green board with the R numbers on it. I've had a little look around but can't find evidence of where it has come from so I am asking if anyone here knows which socket it is meant to plug into?

Cheers,
Burf