The cable should be held in place on the bottom of switch is small bolt and retainer, it should be flush with the outer skin and should hold it firm, the switch however can have the cable move back and forth for an infinite kind of adjustment, but it should still hold the cable, I would maybe disconect cable and see if switch is pooched, it should toggle back and forth pretty easy, check that first also at the same time check to see if when you switch it, the tail lights blink!! this way you can eliminate things, the disconnected wire should move real free when disconected, did you try that and see that it is smooth with no binding or obstruction? if good try switch, that too should move freely and function on your lap, try that, if all works, double check how tight the cable is retained by the switch its good really, but you can slide it by hand if you try, but not with more force than the mechanics allow, really a simple system, oh and talk to it, its like a plant!