The battery motor included in the Classic K'NEX 70+10 model Motorised set and the K'NEX Motor Add-on pack for 50- or 70-model set has a black three-way switch on the top, which allows the motor to be run in either direction.
It requires two AA batteries (not supplied).
To insert batteries into the motor, first use a small screwdriver to loosen the screw.
Then insert 2 new AA batteries (LR6) into the compartment with the correct polarity (+/-), as shown in the photo.
Please also view important information about batteries