Stairmaster Mechanical System Troubleshooting for 4000PT

This procedure covers troubleshooting the mechanical system, which includes the drive system bearings, sprockets, pulleys, belts, and chains for the Stairmaster 4000PT stepper.

Procedure:

1. Remove the side covers. WARNING: TO REDUCE THE RISK OF INJURY, DO NOT OPERATE THE MACHINE WHILE THE COVERS ARE REMOVED. DO NOT DEPRESS OR RAISE THE PEDALS WHILE ANYONE'S HANDS ARE INSIDE THE MACHINE.
2. Remove the Poly-V belt and inspect the belt for cracks, fraying, or any other unusual or excessive wear.
3. Spin the alternator pulley to check the bearings. 
   1. Replace the alternator if any clicking or grinding noises are heard.
4. Inspect the alternator pulley for wear.
5. Tighten the transmission pulley set screw to the flat side of the transmission output shaft.
6. Remove the drive chain and inspect the chain for frozen links. 
   1. Replace a chain with frozen links.
7. Tighten the transmission drive sprocket set screw to the keyway in the transmission input shaft.
8. Spin the transmission drive sprocket input 1 complete revolution.  The transmission pulley output should turn 19 revolutions. 
   1. Replace the transmission if any clicking or grinding noises are heard during rotation or the drive ratio is not 19 to 1.
9. Remove the step chains and return springs from the mainframe of the machine.
10. Inspect the step chains for frozen links and the springs for corrosion. 
    1. Replace a chain with frozen links and replace a corroded spring.
11. Make sure that the step chain connection points pivot freely and have no vertical play.
12. Remove the pedals, pedal arms, and leveling arms, and clean or lubricate as necessary.
    
    1. Step chain connection point should be cleaned & lubricated weekly or every 70 hours of use and every 3 months or every 900 hours of use.
    2. Pedal arm shafts need cleaning every 3 months or every 900 hours of use.
    3. Leveling arm attachment bolt/shaft needs cleaning every 3 months or every 900 hours of use.
13. Verify that the clutch sprockets of the hub assembly spin freely in the forward direction and lock in the reverse direction.
14. Inspect the hub assembly for wear. 
    1. The drive shaft sprocket should not move up and down or side to side.
       1. Replace hub assembly if necessary.
15. Clean and lubricate the drive and step chains with 30W motor oil.
    1. Both drive and step chains require cleaning and lubrication weekly or every 70 hours of use and every 3 months or every 900 hours of use.
16. Reinstall all parts, ensuring the proper tension of the Poly-V belt and the drive chain.
    1. Alternator belt - 1/4" belt deflection.
    2. Drive chain - There should be a total of 1" to 1-1/2" (2.5 to 4.0 cm) of play, up and down, at the slackest point in the chain.