On the side of the pressure switch it says Auto, Start, Off , but there is no trip lever. Plus as Don says there is normally two sets of wires going into the pressure switch and they normally do not go in the same hole.
A lot of times they use the cover for the M4 switch on the regular switch. It just doesn't have the little lever.
And it is possible to wire a pressure switch through only one hole.
I am still guessing the pump saver is shutting the pump off on low amperage, or the overload in the motor is shutting it off on high amperage. A clip around amp meter will tell you which is happening.