Hall Sensors in Series Circuit Problem

The circuit has two hall sensors that monitor the lift positions of independent pneumatic actuators. They are in series where the output of Sensor 1 feeds the GND of Sensor 2 and then Sensor 2 feedbacks to the tool. The time to lift is monitored and must be maintained at roughly 2 secs or positioning of the item can shift on the lift. Needle valves control the lift speeds. The tool will fault if it sees a lift time of less than 1 second (configurable). The problem with the circuit is that it will only create a fault condition if both lifts are faster than 1 second. Either lift can be super fast as long as the other is greater than one second and no fault will be generated. Can anyone think of a way to modify the circuit to allow independent monitoring? I was thinking the outputs of both sensors could be fed into a simple circuit that won't pass the signal on unless both see lift position within about .25 second of each other.

Thanks,
KJ