HP8648A Repairing flex PCB, ideas?

[Mr Simpleton]

OK, so I got a nice lil' signal generator... and at first all looked fine, but realized some of the front panel buttons were not responding. It is rubber buttons that comes in contact with a conductive pattern on a clear flexible plastic carrier. After some digging I found that one of the conducting traces leading to some of  the rubber buttons had a very very thin crack. Not even visible with 3x loupe, but verified with tracer. What would be the best way to repair? Conductive silver paint?? It's not the actual pattern behind the button but the trace towards the button. Soldering may be a bit risky, wouldn't the  plastic sheet melt?

[free_electron]

conductive silver paint.
if you touch it with a soldering iron it will go 'poof' and then it is game over.

[edpalmer42]

You could use the paint that's used to repair the rear window defrosting grid in a car.  It's basically copper rather than silver and it's produced in greater quantities so it'll be cheaper than the silver paint.

Ed

[Mr Simpleton]

Silver paint it is Good feeling now that I did not bring out the soldering iron despite 2 am  and brain in hibernate 
Only need a ml or so...