The kickbacks are located on either side of the pindeck. They serve to keep deflected pins from flying out of the pindeck. Pins that deflect off either of the kickbacks can rebound back on to the pindeck and knock down standing pins.
Money that is paid to someone illegally in exchange for secret help or work A return of a percentage of a sum of money already received, typically as a result of pressure, coercion, or a secret agreement.