Here is my trouble

:I have an Aristo D2 HI V54 220V cold light head on my VXL45 Beseler.
As I start a printing session saturday, the head did not light on...

I open it and found that one of the white soldered cord was disconnected.

Looking carefully to the head connexions, I guess I have located the solder spot, but without an electric diagram I could not confirm it.
The uploaded picture shows the disconnected cord (red arrow) and the possible solder spot (red circle).

Could somebody help me?
Thank you