[Kent]

I have found that if my bike is unused for 2 to 3 weeks, the rear brake light stops working. I am 99% sure that the cause is the "switch plunger" having some stiction issues - it doesn't release fully when the pedal is depressed. It's easily fixed when is manually push it in and back with a flat screwdriver blade. Once it starts working again it works consistently until it sits again for a couple of weeks. I've thought of spraying it with WD40 but don't want to contaminate anything inside the switch mechanism. Anybody seen this issue or have thoughts?
Thanks,
Kent.

 

[Max Kool]

A light spray of WD-40 will work. Most likely just some crust built up.

 

[Hawkeye]

I wouldn't use WD40. I'd use ACF-50 or another product like it which is meant for use on electricals.

 

[vincelp]

You can also check that the pushrod, which transmits the pressure, is still enough greased under the plastic cover.