[Coco] Mylar trace repair question

[Ron]

Hello everyone,

I have a Coco 3 keyboard that appears to have some broken traces midway 
between the end of the cable and about halfway to the entry of the 
keyboard enclosure.  I can't see the breaks, but a continuity test fails 
for about 3 or 4 of the traces (for that section of mylar).

I've read about people doing this repair using conductive pens.  Any 
recommendations for a good one?  I see many folks complain that they 
can't draw fine lines with these and, in most case, need to make 
templates.  I saw the post from Chris Osborn (on 4/23/2015) but didn't 
indicate the brand of pen he used.

In any case, I would certainly appreciate any advice.

Thanks!

-Ron