Bob, I see we also explored the PRS.5 and PRS.7 switches a year ago.
The only other thing I can contribute is the PRS.5 switches are repairable where the PRS.7 switches are not. When opened up, the PRS.5 switches contain a half dozen or so individual pieces than can be cleaned of tarnish and made to work as new. Sometimes there are broken brass connectors between the terminals, possibly from overloading. Those connectors can be successfully repaired with solder.
The PRS.7 seem more robustly built, but the internal components are incased in a one-piece plastic housing. I don’t see any way of servicing the internal switch components of a failed PRS.7.