Main Pivot
The main pin and bush keep the opener shank running straight and true, so play here throws the whole unit out. Get it clean, grab the arm and check for side-to-side movement — a fresh pin and bush show none. Move it up and down for smooth travel with no stiffness. If the arm swings in a circular motion the bushes are done, and worn parts left in place chew out the housings, so replace the pin and bush before the housing takes damage.
Applies to: Main Pivot Bush Hardened AA133BH · Main Pivot Pin Hardened AA133PH · Main Pivot Pin & Bush - Hardened AAMPBH