Gentlemen:
Reverse the house wiring at the rear of the connection block to clear the problem on one set, or reverse the entire line at the NID to clear the problem in the whole house. I would not be so concerned that your LEC will reverse the line again, as long as no activity takes place due to a service order or repair request. Some people in my antique telephone collecting club (
www.ATCAonline.com) who collect and operate these polarity-sensitive phones simply put a DPDT switch at the NID, and when the lunatics at the phone company reverse the line, they just go downstairs to the basement and throw the switch to the other position.
The White/Black wires have been used for the lamp since the advent of the (non-modular) Trimline in the 1960's. The Princess phone, which predates the Trimline, used Yellow/Black for the lamp for a short period. The first Princesses (the "A" models) were not equipped with a ringer, so 4 wires were sufficient. When the next generation of Princesses (the "B" models) arrived, equipped with internal ringers, the necessity for a 5th lead became an issue, and the Yellow lead was assigned for the ringer for uniformity across the entire family of x500- and x700-series phones.
The polarity guard must be installed inside the set, after the ringer. It will not pass ringing current, (since it is a full-wave bridge, it will rectify it, and the ringer, being an A-C device, will not operate) so it cannot be used external to the set.
Don't put one outside the phone, unless you want to come back here and ask us again why the bell isn't ringing.
The original Princess phones had a lead weight installed in the area of the phone where the ringer should have been. The phone was invented before the ringer that would eventually fit inside. When field forces disconnected "A" series Princesses, and the sets were sent back to WE to have ringers installed, there was a cottage industry at the field level of removing the lead weights, which found their way into fishing tackle boxes and Pinewood Derby cars.
Our motto where we worked: "If the phone company doesn't stock it, you don't need it."
Hope this helps.
