Head motor gear reducer failure.

The gear reducer in the head motor assembly prematurely fails. The weight of the head assembly with or without a patient seems like more than the motor design can tolerate. I have discussed this with the motor manufacturer (U.S. Motor). How can I easily test the limit switch assembly in or out of the bed to verify operation. Are there proximity sensors along the switch strip to monitor position or just end travel limits? I suspect gear damage begins when screw over travels the up limit. Thanks for any related experience help.