Several things allow the limit switches not staying off or not work at all and then the thermal breaker can activate because motor(s) draws way more amps to stall out.
If a Motor draws ~ 4 amps running (Gen2 is so. Never check Gen1 system.) then stall amps at End of Travel are 2 to 5 times that. If the Gen1 breaker fails too then will burn out relay(s), the motor, or worse and never blow the Fusible Links. Most Relay burning is because the motor have problems or low volts. (See my Cave,
Electric Motors )
Some examples:
Not staying off can be a "rebuilt" motor w/ problems like too much lube or no/wrong buffer/bumper in the output gear. Motors need to load the output shaft and stay loaded to keep limit switches off.
Limit(s) Not working then will heat the breaker to shut off the motor.
Both are big problems because only takes seconds to minutes to repeatedly "wind up" the motor to shut off
or repeatedly trip then auto reset that breaker. Either/both happening will easily kill the battery fast.
Gen 2 system is much better but not perfect. Is "Easy" upgrade and if motor(s) are bad you can get
New motors thru AZ or anyone carrying Cardone w/ a lifetime warranty.
See my Cave,
Gen 2 HL Motor------------------
Dr. Ian Malcolm: Yeah, but your scientists were so preoccupied with whether or not they could, they didn't stop to think if they should.
(Jurassic Park)
The Ogre's Fiero Cave