I've had a problem with the brake light staying on, and only going off if I pump the brakes a number of times. It will then come back on a few minutes later, and will only go off if the brakes are pumped again. Because of this, I definitely don't think it's the master cylinder.

I was told by the prop valve vendor to simply loosen the sensor 1/4 turn and that should take care of it.

I haven't tried this yet, but there's another issue too. The rear brakes are slow to apply, they don't apply until I've pumped the pedal a few times. (i.e. the cylinder doesn't even move) Does this sound right, and maybe I've just got them adjusted too loosely? (I tightened them with the tool pretty tight, and then backed up the car and stopped at least 20 times) Or does it sound like it's a bad prop valve? Help!