I had an issue with a Mac 104 before that was caused by corrosion. The 104 board had severe corrosion come to find out. The door board would send full power in opening direction, causing what I have deemed the "cookie monster" effect. The motor would just go into full speed wide out opening. The doors would repeatedly slam open and shut, due to the drive sheave having enough force to roll completely over. It had enough energy that it bent the jam. It was the scariest thing I have seen. The force would have killed someone. I am glad I was onsite to see this happen and shut power down.
It was this time of year it happened 3 years ago I believe. On the gulf coast, we have severe condensation on elevators located on the beach. It is something I am constantly checking with those units.
