Wiper Motor have 3 sp switch with 2 pd motor

If the motor stops at the correct position the blades wouldn't move downward at switch on, they would move upward. This park at bottom of stroke is adjusted by rotating the stop cam mounted on the outside of the gear box. Hash marks stamped or cast ( I forget ) . Its a sensitive adjustment too.
Everything you want to know about the various wiper systems is in a factory service manual but its all quite complicated.