I'm not saying your wrong, in fact you're probably right. What I'm saying is why "try" something when you know the problem is with commutation? Those motors only cost a couple hundred bucks and considering there has been multiple calls for the same door problem, the customer is already starting to question you and your company's ability to maintain their elevator, so just spend the couple hundred bucks on the sure thing and have a happy customer paying full maintenance for years to come.