Help removing fuse box W126

[MS Fowler]

I am trying to troubleshoot an electrical problem. On my 1982 300SD, the rise and fall, as well as the recline on the passenger seat do not work. It seems that I do not have power coming thru the red w/ white stripe wire. I have full function on the driver's side seat, so I think I have a break in the wire itself. I was thinking about cutting the red/white wire and using it to pull a new wire from the switch to the fuse box. Has anyone tried this?
I need to get to the underside of the fusebox to solder the new wire in. I do not need to fully remove it I just need to turn it over.
I found the 2 screws on the side of the front of the box, just behind the bulkhead. It feels like the box is still screwed in somewhere. Any help?