This can be a big problem with a Mac operator, especially on mods. There is too much travel for the opening size. You set the operator position based on full close so the linkage is in a straight line but When it reaches full open it hasn’t come close enough to 180 degrees to hold the door open against any about of spirator tension. I have tried cheating the operator over towards the close but then it won’t hold close which is worse. Some things I have thought of but never went through with are adding a spirator to the car door to counter that of the hall, rigging some kind of magnet to hold the door full open, or altering the linkage to give it less overall travel. But a better solution is an MOVFR.