When I first built the layout in 1998 these switches were pretty new to the market, and offered flexibility in that both the straight and curved legs had optional extension tracks. So I designed a few pairs into the track plan and whipped the layout together. it didn't take long to discover that one pair in particular placed heel to toe (with none of the extensions installed) had an ugly dead spot that caused quite a few engines to simply go dead. As seen below the distance between the outer marks and the inner ones is 6-1/2" to nearly 10". So this meant that any engine with only 2 rollers that were spaced in that range, went dead going through. This affected many MTH SD's, geeps, trainmasters, etc, as well as others. Not fun.
One thing that helped was to hit these switches at bobsled speed, but that isn't very realistic. For some engines I was able to replace the single roller pickups with dual roller pickups, and that helped quite a bit. But still it didn't fix all, and not as good as I would like. So today the "final" fix got done. As seen below I extended the straight-thru path hot rail by about 1-1/4" for each switch. I used 5 thou brass shim stock which I had in the garage shop, trimmed and bent to shape. It is formed to fit the rail head and extends down each side about 3/16". Where the plastic is wider than rail width it is laid flat on top. The angled cuts are so as to clear wheels running through the turnout track, and not to cause a short.
The shim stock is glued to the plastic and rail stubs with Goo, including the flat parts. Finally I soldered the track ends to the track stubs for continuity as seen below. The results so far are about 98%. The dead gap is cut to between 8" to 8/3/4" and that's about as good as it is going to get. Anything with dual roller pickups doesn't miss a beat. Those with single roller pickups spaced in the range above still make it through, with only a slight hesitation. So all good.
My only regret is that I didn't do this about 20 years ago. Oh well, never too late to fix trackwork! 
