power steering no assist on 1990 Chevrolet 3500 Pickup

87 chevy one ton 4x4 with 454 had fluid leak at gearbox. replaced gearbox and filled with fluid now i have no assist.

Asked by for the 1990 Chevrolet 3500 Pickup
Check lines for blockage. A piece of old gasket or something could be blocking the fluid. Look in the hole where line goes into box. Lines could be plugged by debris or kinked, unhook and turn pump to check flow from pump. Verify pressure line in correct port on steer box.