Check bed and fence for gaps

• 1). Unplug the jointer. If you are not the only person in the shop, make sure everyone else knows the machine must remain unplugged.
  
  
• 2). Place your straight edge flat on the jointer's out-feed bed. Run the feeler gauge between the bottom of the straight edge and the bed.
  
  
• 3). Place your straight edge flat on the jointer's input bed. Run the feeler gauge between the bottom of the straight edge and the bed.
  
  
• 4). Place precision square on the jointer's input bed. Butt the square up against fence. Using the square as a guide, adjust the fence to 90 degrees.
  
  
• 5). Starting at the front edge of the input bed, hold the square flat on the bed and slide it toward the back of the jointer while checking for gaps between the square and fence with the feeler gauge.