The employer is given credit for a prior injury if the prior injury resulted in the loss or partial loss by amputation of a member including the hand, arm, thumb, fingers, leg, foot or toes. If workers’ compensation payments were made for the partial loss of any such member or for the partial loss of sight of an eye, then the disability covered by the prior payment or amputation is deducted from any award for the subsequent injury. There must be either prior amputation or prior payment to enable the employer to claim credit. Mere prior disability does not justify a credit. Accordingly, if a prior condition is the result of a work injury with the previous employer that was not settled on permanency, and the employee sustains a work injury to the same part of the body aggravating the prior condition, the employee is entitled to be fully compensated for the subsequent injury.