"controllers" are the Bachmann Speed Controller with Plug-In Wiring... what is odd is that this layout worked for weeks without any problems...now, it can only go in one direction...any help would be appreciated

after using the EZ Track layout ( N scale) for about a month with no problems, my track only goes in one direction now... don't understand why?... it's not the engine either, because all engines only go in one direction on this EZ Track layout... when I slide the switch over to go the other way, the engine just dies... also, on another EZ Track layout, all engines work as designed, both forward and reverse, so it's something to do with THIS track... my Plug 'N Play controller is the type with the 2 red wires coming out of it to power my switches on the track (all switches are working fine)... I have swapped out controllers, tried different engines, unplugged and re - plugged the power from the outlet to the controller, tested other N scale track layouts... but I'm at a loss... any help would be appreciated...

both of these switches do not work properly all the time - my cars with longer wheel bases work the best, but there are times these fail too  - the short wheel based Santa Fe locomotive rarely works on these crossovers  - speed of the train do not solve the problem either - medium fast or super slow (it does not matter), the success of the train to cross over is not always successful - there are times the train goes around OK, but then on it's 3 or 4th pass, the crossover fails - any ideas or suggestions? - I have a 5' straight track between the left and right crossovers