The one thing you’ll never know is if the first shop you took it to changed the belt and routed it wrong. If they replaced the motors and routed the belt wrong, it wouldn’t work properly for them. They threw in the towel and you had to go to a second shop. I hate to say this, but there is a shop near me that has done things like this for many years. One time they told the customer her engine was bad and replaced the engine. I told her that when she picked it up, to make sure she got the bad engine back for parts. I tore the engine down and found nothing wrong. She went back to ask them about this, but they claimed she’d been give the wrong engine. When she showed them her owners. manual with all unit and engines numbers written on it, they ended up giving her all money back, plus both engines. It helped when she let them know her brother was an attorney in town.