Problem with 0-27 tubular switches

It sounds like there is a brief interruption of current, or more likely a short circuit when traversing the switch. Try to find out which by closely watching other bulbs on the track or transformer.
If interrupted, you may have loose connections at the track pins or an internal loose connection, perhaps requiring jumper wires around the switch with another CTC lockon.
If shorting, a strategically placed small piece/strip of electrical tape on the offending (ground)rail may cure the problem. Often, the pickup rollers on some locos bridge the center rail to a ground, causing the symptoms you are having.
Try moving the loco(s) through the switch(es) in neutral to help narrow down the trouble. Keep your other hand on the throttle in case the engine gets away from you.
Rob