Looking for a fuse box/relay platel for an '82 coupe

[DBF]

As the subject says.  I'm experiencing a rather annoying anomaly in that the car dies, everything quits.  No power to anything but the radio (as it's wired direct).  I then have to pull over and reach under the dash and wiggle the 'big' red wire and everything powers up!  I've been plagued with electrical gremlins since buying the car 2.5 years ago and I'm quite sure all the years of a leaking windshield has finally taken a toll on it.  I've had it out a couple of times and it's pretty grim looking.
The car is an '82 coupe and according to etka, the part number is 171 941 821 C.
Anyone out there have one lying around that's not all green inside?  Huw?
Thanks in advance,

Dan