rbakerphoto,
I think this excerpt from a Trainboard.com member may help.
We are talking about the standard PECO under roadbed PL-10 switch machine here aren't we? You should have 4 terminals on the PL-10 switch machine. You should have one wire that goes from one terminal to another and then back to your power pack. This is your common (ground) wire. The other two terminals should have one wire attached to terminal. These are the power (hot) wire/terminals.To do anything with the switch machine it would be a whole lot easier to remove the switch machine from the switch points. Just unbend 4 tabs that are on the top of the switch motor. These tabs go through the switch ties right by the points. Just straighten the tabs up with pair of needle nosed pliers, and the switch motor will fall out.Once the machine is out, check your terminals, the one with the broke off wire can most likely have the wire resoldered directly back to the terminal.
Jon
Yes, the two terminals on one long side should be wired together as the "common" lead. The other 2 on the other long side go to the outer two pins on a single-pole, double-throw, (SPDT) momentary contact switch. The center lead of the SPDT goes to one side of the power supply, and the common lead from the switch machine goes to the other side of the power supply.
With Pecos, I find that a capacitive discharge circuit makes them work a whole lot better. It also protects them in case that SPDT switch fails to dis-engage. You can build a CD circuit for a few dollars in parts, even from Radio $hack. Google around for a circuit diagram. It's literally just a couple of capacitors and resistors, and you can drive it from the same power supply. (For an AC supply, you need to add a bridge rectifier, again, a cheap part.)
It takes an iron man to play with a toy iron horse.