On my first visit, I found the fan blade off the fan motor that cools the Mag.Installed new fan motor and secured fan blade. Reasembled MW and tested it. It tested ok. I went back because now it cuts off after running it for 6 minutes as opposed to two minutes on first trip. Upon inspection I found fan and motor intact however doesnt seem to spin as fast as I think it should when in use. Has anyone come across this?