running light circuit Fuse blowing (!!)

[Jean]

All the "Old" BMWs do not commonly use a chassis ground for the lights. You will find a BROWN wire coming from almost everything that's not on the actual frame. THAT's the GROUND. In the headlight bucket, the brown wires ARE collected and DO connect to the shell, however, BUT there is a common brown wire going from there to the frame ground near the coils, or should be. Everything metal is "ground", but they are also connected together by a grounding wire.
If you haven't already discovered...Green wires are hot when the switch is on.
I think when you smoosh the headlight assembly back into the bucket, you are touching one of the hot terminals on the fuse board or the relay with the protruding clips that hold the headlight/ring together.
It may be that you are just displacing OTHER bare terminals when the headlight is pressed into the bucket, and when you remove it, they spring back...