Chamberlain GS400D Owner's Manual page 18

CHECK PISTON TRAVEL
8
Visually check the clearance. Holding the gate firmly, slowly walk the gate to the fully open position. Check for
pinch points at the post mount area.
Allow a minimum of 1/4" between the post bracket and operator. Adjust gate bracket if the piston marks are not
visible in both the open and close direction. Tighten both bolts after final adjustments are made. Bolts should be
fully seated into the brackets.
NOTE: If gate does not open and close completely, adjust the position of the gate bracket.
Installation
Minimum of 1/4"
18