Conductive pen alternatives?
 

I've got a few keyboards where I need to go back over the traces, especially where the traces on the flexible plastic meet the traces on the circuit board for the keyboard. Does anyone know of a reasonably priced alternative. Pencil graphite seems to work, but it's very temporary. Is there something I can use that won't cost me twice what all the keyboards are worth but is relatively permanent?

Old clicky type keyboards, I used flattened solder...but those are several layers of plastic with foil traces between them.

Fine silver solder? Or foil tinsil? A mix of superglue and graphite powder/fine metal powder?

This may work for you: Rear Window Defogger Repair Kit

You could try conductive epoxy. Or Nickel Print, which is a conductive paint marketed by GC Electronics. I use it to paint the cavity of electric guitars to shield the guitar electronics.

Conductive copper never seize might work too, but I like the conductive paint for repairing defrost wires.

I've used the rear window defogger paint on CPU's in the past, it works pretty well, and is easy to apply. I would think it should work fine on flexible PCB's as well.