Your most welcome. Since it is ALL of your engines that have the problem I would highly suspect the switch(s) myself. Unless all of your engines are the exact same engine, model, design or what ever you call it (having the same setup with their pick up rollers is what I mean here). I would guess that the PS3 engines have the same pick up roller as the PS2 engines of their same types? Engines not offered in PS2 and new to PS3 might be different?
Dave Hikel has posted here somewhere on the OGR forum a bunch of tips for using the Scaletrax switches. They have had some problems. He probably knows as much (or more) about the Scaletrax stuff than anyone and he has at least a couple of posts around here describing problems. He has also worked with MTH to correct the problems and also posted the fixes here on the forum. Might try looking for Dave's posts here and see what he has to say. I would offer a link, but I don't recall the threads they were in? If I do find them I'll post a link.
I believe the newer Scaletrax switches (last year or so) are said to have all of the fixes Dave recommended. If that is the case then maybe Dave's posts won't be of much help? Probably still worth reading though, he's a very informative guy. I have Atlas track and Scaletrax is the only track type my LHS doesn't carry. I have never even seen a piece of it in the flesh.