I just bought a second ZW-C with two PH-180's on eBay for less than the value of the bricks, including shipping. One bell button is missing, which I can fix and parts are available. The seller said he doesn't know if it works. I will test it and find out if there is any issue. It even came with the jumper plugs, which are almost always missing. I have plenty of PH-180's, so I will probably sell two assuming the ones I get work. I have never found a bad PH-180 though.
George