Is there an easy way to figure out where on the painted on "wires" is the bad
part on the rear window defroster ?

I bought a kit containing a tiny bottle of Copper Metal paint to repair my
RW Defroster, but trying to see the discontinuity is nearly impossible.

I know which ones (2 of them right where I look in the rearview mirror!) are
bad, but WHERE at on them !?

I looked with a magnifying glass and the wires look OK.

DoctorBill

Use a test light. Ground it to one terminal and start on the opposite side with the defroster and key on. Carefully touch the grid working your way up or down until you find no power. Then work your way across from the last grid you had power to find it.

The test light can scratch the grid, so again........... Be careful!

Do what Johnny said but use aluminum foil on the test lead to protect the grid!

A DVOM will also work. You should see an even voltage drop working across the line you're testing. 0V = open circuit.

-Matt

I shall try it....

Wish me luck !

DoctorBill

PS - Why do things like this always fail exactly where one
looks thru the window !?

Like bird crap or bugs splatting exactly in your line of sight !

Entropy at work....