I think it's more like this-- note that I've flipped all D3 from your diagram to the actual orientation shown on the photo of the PCB.
D2 is a flyback diode across the motor coil. Don't forget that GND connection on 4 or the other diodes may be damaged when SW1 opens or if SW2 is released before SW1 closes.
simulate this circuit – Schematic created using CircuitLab
SW1 is open when the motor is in the park position, so no power is on the motor.
SW2 is held long enough, powering the motor through D3, for SW1 to close, powering the motor through D1.
When the motor reaches the park position, provided SW2 is still released, it stops because SW1 opens.
D2 is a flyback diode as discussed above.
It's not obvious to me why they bothered with diodes D1 and D3 at all.