I have been having electrical discontinuity problems with many many MTH NIB RealTrax rail, all the solid rail kind, I do not buy the later hollow ones.. I purchased a bunch of the solid track ones a few years ago, either through mail order, dealers, or through RTR Rail king kits such as the imperial SD70Ace sets.
After connecting a loop, I would run a test train. In most cases the loco would run ok but after a few laps, it would stop dead on its tracks 
and goes into shut down. Initially, I thought it was either the power supply or the PS2 loco. After hours of investigation, I found out it was the track itself that had intermittent electrical connection and always in the center rail. Seems that the electrical spot weld was not done properly at the factory. When I checked with an ohm meter at the brass/copper tabs, I would find either an open circuit or a few ohms impedance. Again after careful examinations, I found out that the weld was not done properly. Pushing down on the tabs with the multi meter probe would get about 0 ohms. If you look closely at some of the shots, you will notice that the "dimple" of the electrical spot weld is shallow in the center rail. The outside rails has a deeper "indent".
I did not know what to do since I had bought these tracks a while back, no warranty. Regardless I wanted to fix it myself anyway. I was going crazy and puling what's left of my hair not knowing what the problem was in the beginning.
I decided to use a drill to put a small hole in the center tabs and drop some solder in there. So far it is working well, but I am not sure of the long term result. The solder is not the best conductor but it helps keep the center rail and the end tabs touching and making electrical connection.
Today, I opened a new box of about 10 straight sections, only TWO were ok, the rest I had to fix...Now that I know what the problem is, I check every single track before use. I check all THREE rails/tabs for 0 Ohms or so...
Arrow points to the problem area
Two out of ten were ok. Ten not shown here.
You see how it is always the center rail. Black arrows pointing to problem area.
Use a drill to make an indent. Make sure you go through the tab and into the rail a little bit. DO NOT drill all the way!
Solder time! very high temp is applied quickly to prevent melting the plastic!
Now They are all OK. . Note the different color tabs, I like the darker tabs, I think they are better quality brass/copper than the yellowish tabs, what ya think?
In complete contrast, I had used Scaletrax and never had a connection issue....I do prefer MTH Scaletrax and my future layout will be using them.
No bashing preferred!
