OT:5Vdc prox sensor

I have a three wire unsheilded M12 prox sensor at one of our customers. It has been sorely abused over the years and I attempted to replace it. The partial part # leads me to believe it was an obsolete Balluff PNP. I crossed it to an Omron and installed the replacement (surprise, surprise!) it did not work. Checking the power supply I found it was running on 5 Volts DC. Balluff insists that none of their sensors would ever have run on that voltage. The Part# BES 516 356 E4 Y5 is my best guess as to what remains of the cable (run into various gears a few times (I'm not kidding). Has anyone ever found a three wire M12 prox that will work at 5Vdc?

I have never heard of a M12 prox that is operated on 5 volts.

The 5 volt power supply, does the label say that is the output voltage, or is that a meter measured voltage.?
Reason for the question is, could there be a short and the power supply is lowering the voltage, so that the current is not exceeded, switch mode power supplies can do that but usually go to a lower voltage than 5 volts.

Disconnect the wiring from the power supply and measure the no load voltage.

This prox is hooked up to an OEM counter the customer had purchased with a handmade photosensor of some kind. The photosensor died and someone (previous technician) had stumbled onto this sensor as a subsitute. Opening up the counter I found a 5 volt regulator, and I have never seen a Prox running on 5Vdc either.

Mike