What kind of drive do you have? Generator? DC motor? VVVF? SCR? What is happening when it goes into fault? Stalling at the floor? Not taking off? Type of elevator, etc?
If it has a drive, it could be as simple as a drive parameter being wrong. We had an MCE Engineer come to teach a class at our office and I suggested for the on the job portion of the class that we go to that job with the MLT prob (since it had been going on for a while and I inherited the problem). We went out ther and he found it pretty quick...
The contactors used by MCE seem to be undersized and only last for a year or two. Start by checking the M contactor and the brake contactor with aux contacts. Ohm them out and see how much resistance you have on each pole. As stated above...What type MCE would narrow it down.
MLT faults can be caused by a lot of stuff. MCE starter auxiliaries are crap if these are the kind you can change one at a time. Typically you will have a few NO contacts monitoring drive contractor on as well as a few NC which monitor that the M switch dropped out. They tend to be junk.
