Bachmann HO auto-reversing E-Z Track system no longer works

[DRC]

Hi, I have a Bachmann HO auto-reversing E-Z Track system. It's approx 8 years old and has stopped working properly. I've tried troubleshooting the problem and discovered that it appears to work fine if I remove all of middle track pieces marked "A" on both ends and simply connect the two pieces with the "reversing trigger notches together" - the sections that have a B on one end and A on the other end. When I place a section with "A" on both ends back in the middle the locomotive will run for a few seconds and then die. The track has been cleaned and is well connected. The locomotive has also been cleaned and lubricated and runs fine on the track at the local hobby shop. I'm at wits end. Does anyone have an idea what's wrong? I'm hesitant to shell $$ for a new track and discover that the problem persists. Thanks!!!!!