Will not walk - Mattel Little Mommy Walk and Giggle Doll

If the walking belt slips when walked on, first remove the key and UNPLUG THE POWER CORD. Using the hex key, turn both idler roller bolts clockwise, 1/4 of a turn. When the walking belt is correctly tightened, you should be able to lift each edge of the walking belt 2 to 3 in. (5 to 7 cm) off the walking platform. Be careful to keep the walking belt centered. Then, plug in the power cord, insert the key, and carefully walk on the treadmill for a few minutes. Repeat until the walking belt is properly tightened.

If the walking belt slips when walked on, first remove the key and UNPLUG THE POWER CORD. Using the hex key, turn both rear roller bolts clockwise, 1/4 of a turn. When the walking belt is correctly tightened, you should be able to lift each edge of the walking belt 2 to 3 inches above the walking platform. Be careful to keep the walking belt centered. Then, plug in the power cord, insert the key, and carefully walk on the treadmill for a few minutes. Repeat until the walking belt is properly tightened.