OK, guys, here we go on 1122 switches. I recently repaired a bunch of them and found problems inside all of them. Some of them had high resistance connections that actually melted the plastic.
What is necessary to fix them is to remove the bottom plate and solder all the electrical connections. To remove the bottom plate, you must drill out the rivets. The V in the center of the frog is riveted to the bottom plate, and to allow it to be held in place, you must drill and tap a hole in the frog. I use a 4-40 tap and a 4-40 filister head machine screw. Use WD-40 as cutting oil. Otherwise you may break the bit or tap. Don't ask me how I know these things. The frog is die cast zinc. Drill out the rivet for the ground terminal and for the other rivet that is inside the switch motor housing. Bend the tabs for the outside rails up so you can remove the bottom cover. Inside you will find some crimped electrical connections, and if you have a meter, you can discover which one is bad. However, solder all of the connections. Otherwise you will be taking your switch apart again in the future. The plastic that the switch is made from is soft and cold flows over time and so the crimps become loose. Everything inside the switch that is connected to the center rail should be soldered together. The center rivet in the fat center rail should be soldered to the rail. This rivet is the electrical path for power to the other center rails and the switch motor. Make this solder connection as smooth as possible because a mound of solder will push the pick up roller to the side and short it against the movable points. Check your work with a meter before you put the bottom cover back on.
When you put the bottom cover in place, the first thing to do is solder the ground terminal to the bottom cover. This needs to be tight so it makes a good connection with the ground tab coming out of the switch motor housing. I used a pair of channel locks to clamp the screw in the hole so I could solder it. This can be done with 2 hands, but it is easier with 2 people unless you have a 3rd arm. You need to polish everything before you solder it so the solder will stick. Solder the tabs for the outer rails to the lower plate at one end of the rail. I didn't replace the rivet inside the switch motor, but you can replace it with a #4 machine screw if you want to.
The terminals use a 4-36 thread, so if you use a 4-40 machine screw to replace the ground terminal, the thumb nut won't screw on. You could buy some 4-36 machine screws and nuts to use for this terminal rather than soldering the terminal in place.
There are two types of 1122 switches. The earlier type uses fiber pins, and the later type does not need fiber pins. The early type switches use fiber pins in the short outside rails. These rails are used for the non-derailing feature. On the new switches, the long outside rails are used for the non-derailing feature. There is a cut in the long outside rails about an inch from the end. The short end of each rail is connected to the lower plate and they are also connected to the outside rails on the end where the movable points and are connected to the short outside rails that go to the frog. You need to make 6 solder connections to solder all of the outside rail pieces to the lower plate.
Bob Nelson on trains.com has a modification to these switches so that you can supply constant voltage to them and the switch motor is operated by a capacitive discharge circuit. IMHO, this is a very good modification and should be considered for a permanent layout. He went through the modification in great detail for one of the other members including indicator lights on the layout control panel.