Seems my dual braking switch is dead. This is the little grounding switch that screws into the dual braking block just below the master cylinder and let's you know if something is amiss. Anyone got a useable unit or know where I can buy one?

Actually, i have another question. Whenever I bleed brakes or otherwise disrupt the system, I first remove this switch so that the system can reset when everything is equalized. Been doing this on umpteen Volvos since forever. But I recently replaced the master cylinder, which was seeping (I'd rebuilt it some years ago, but I had a new master cylinder in my extensive parts inventory and figured, what the heck, I'm nearly 70, what are they going to do, bury it with me?) and darn if I didn't forget to remove the switch during the change.

What exactly happens in that case? Does the piston in the dual braking block deflect if there is a pressure loss to it's north? I'm a little concerned because when I pulled the switch to test it.... no continuity when the plunger is depressed... and then screwed it back in, I didn't feel any resistance at all. So i'm wondering if the piston is still off center. If someone can school me on this situation and tell me how to tell the status of the piston in there I'd be grateful.