.Replacing and Preventing broken couplings
When the power stand is being operated there is twelve inches of travel. When this travel is at its limit the motor has enough torque to twist the flexiable coupling. The coupling has the ability to withstand this twisting for a long period. However when this twisting is excessive the rubber material fatigues and tears. For this reason care should be taken not to continue pushing the control button after the stand is obviously out of travel.

We also recommend the use of an electronic switching Power Supply. This Power Supply acts like a limit switch and cuts the power when the stand runs out of travel. All Remote Mast systems are now shipped with this type Power Supply    
  Step by Step Procedure to Replace Coupling
You may remove the motor assembly steps 1-5
and ship it back to Chapman Machine and we will replace the coupling for you. Or you may choose to follow these instructions and replace the coupling yourself. The coupling and electronic power supply are available on our parts page.
<Shim here
First stage
Second Stage
Drive Screw
Motor Flange
Remove the (3) set screws and electrical jack nut
1/16 Allen wrench.
Step 1  Lower the Stand Mast to its lowest position.
Step 2  Place the Stand across a table using soft                     towels underneath for protection..
Step 3  Remove the three set screws located in the                    column just above the base.
Step 4  Remove the nut from the electrical jack.
Step 5  Gently remove the motor.
Step 6  Using a 1/16 Allen Wrench loosen the set                      screws from the broken coupling.
Note: The drive screw may be out of reach up in the          column. Use a rod or screw driver to turn it              counter clockwise out but only 5-6 inches.
Step 7  Remove the four screws from the motor                    flange. Gently remove the shaft with the                   flange. If a gear comes out with the shaft do
           not be alarmed, Set it aside for now.
      At this point make sure your hands are clean             and take care to keep parts clean.
Step 8  Place new coupling on motor shaft. Place a            .005 shim (Something approximately that                  thickness like a peice of paper) between                 the thrust bearing and the new coupling.                  Tighten set screw and remove the shim.
Note: If all gears remained in place when flange was            removed, reinstall the flange assembly now. If            even one gear was dislodged then all the                   gears need to be removed using needle nose             pliers and placed on the shaft gear plate.            
Before installing motor manualy run the main Mast tube through its full travel. If it drags or binds the bushings may need reboring. Call 864-226-4028
Step 9  Reinstall the motor coupling to the Drive                  Screw and then push the motor into the                   housing. The 1/4 pockets in the urethane                 motor mount need to be alligned with the                 three holes in the column.
Step 10  Reinstall the three 1/4-20 set screws                      turning them in until FLUSH ONLY.                         The motor needs to float                                         Reinstall the electrical jack nut.
Shaft gear plate
           ( If set screw socket is stripped out you                     may need to place the coupling in a vise                  and drive the shaft out.)
       Then slide the assembled unit into the ring              gear housing. If the assembly will not seat               then you may have to remove the first and               second stage gears and install the cluster on           the shaft plate and reinstall.
        Gently push the unit into the ring gear                     housing while turning slightly..