Im really looking for all the information about this device through experiments and expertiseYou probably won't find any videos on it, it was never a big seller for White's. If you have any particular questions, ask away.
I don't know what you mean by "boxes." A metal box? Then no. The PCL is used to trace wires and metal pipe. You can either directly energize the wire/pipe by clipping the TX onto an exposed portion, or by inductive mode using the TX coil in the lid. With inductive mode you cannot get the RX box too close to the TX coil or you will get direct coupling. It is not at all useful for locating isolated buried targets.Also, its ability to search for boxes and whether it is practical or not