Rear wiper problem

95 chevy blazer rear window wiper catches the rear hatch when you turn it on, if you help it past the rear hatch it works good ,without further assistance . if you turn it off it goes to resting place (below rear hatch ,and when you turn it back on it catches again) WHAT CAN I DO , is the a specific angle the wiper is suppose to lean so it dont catch, thanks

Have you try resetting the arm when it is in park position?
How did that happen/
Has anything been done to it?