Suddenly my brake light lit up all the time and i noticed that the plunger switch thingy hasn't been pressed all the way (but very close from being fully press in). How did this happen? Is it due to my brake pedal height been lowered a bit due to some issue? Or the brake light switch issue ( it works fine though but it must be pressed all the way).

Many thanks

 

I had the same issue after replacing my master and booster my quick fix was just remove the sensor and use your hand to bend that flange a lil closer to the contact point on the brake pedal assembly.