Electrical Gurus I Need Help- '84 300D

Help! My 84 300D (Cali car) lost power to the headlights. I traced
the power and found that there is no 12V+ going to the fuse box for
circuits 11 and 13 (left and right headlights/fog lamps) When I
jumper a hot lead to the back side of either of those fuse circuits,
the headlights come on (with the dash switch on). The car had been in
an accident with damage to the right front fender area but everything
is fixed and I cannot see any obvious problems. Does anyone know where
the power to those circuits comes from? Does 12V go to the headlight
switch first then the fuse box or the other way around? I suspect the
latter but don't have an electrical diagram. This problem happened
last year and I searched for the problem. The lights started working
again without fixing anything (that I was aware of anyway). I suspect
a loose connections SOMEWHERE. I am temped to just run a new power
lead to the back side of the fuse box but wanted to query the group
first. Anyone?