I posted this on renntech but I thought would reach out here also to see if anyone has any tips or suggestions:

1999 996, weekend ride, garage kept, 77k miles
I had a bulb burnt out in drivers side headlight , pulled out to replace and all wires have insulation just crumbling off exposing bare wire. I spend an hour putting some electrical tape where I could but feel this is a temp measure. It seem Porsche does not sell this harness(inside the headlight fixture). Has nay one rewired these or found another solution?
Thanks

 

mine are brittle & falling a part also. I'm thinking of spraying the wire with plastidip to coated

 

I had the same problem. They were brittle with sections of bare wire. Obviously related to the IMSB. I rewrapped the wires, but it was only temporary. Decided to purchase a light unit from LA Dismantlers. It was a much better specimen and did not have any of the yellowing the other unit had. Now one headlight is slightly clearer and whiter than the other.

 

You could try using heat shrinkable tubing like this:

You need to have one end of the wire disconnected so you can slip the tubing over the wire, then you use a Hair Dryer to shrink it on.

 

Cutting off both ends and running new wire is the best way. Get a $15 soldering kit from the hardware store, automotive wiring, and some shrink wrap tubing.

Usually wires that's been exposed can be corroded and less conductive. All of a sudden that 18 gauge wire can act like a 22gauge wire in terms of resistance.