My FXDWG front brake lever isn't pushing the brake light switch to open the circuit.
I am guessing the spring loaded piston in the master cylinder is sticking and isnt pushing the front brake lever back far enough to turn off the brake light.
Before I order a master cylinder rebuild kit, any other suggestions before I move ahead with repairs?
Seems like this is a common problem.

 

I've overhauled a few of these where the piston was either corroded or gummed up with varnish to the point that the spring couldn't overcome the resistance. It is common.

 

Probably correct, this bike sat for a few years before I bought it.

 

This only make sense if you push out on the lever and the light goes out..

 

Not uncommon for the plunger on those bikes to get broken when someone takes the perch off. I'd check and see if the plunger is hosed.