Be sure the power and the pressure is off to the system. You will also need a .9 mm Allen wrench to remove the knob and perhaps a ½ wrench or pliers to tighten the potentiometer.
Step 1: On a clean work table lay out the MPPI and the Allen wrench. Locate the Pulse Duration knob and rotate it counter clockwise back to the zero position. The lock lever should be in the upright position as seen in figure 1 to allow the smooth rotation of the knob. When you get to zero if the knob passes and continues to 14 or any number other than 1 to 10 then the knob has slipped its keeper ring, as seen in figure 2.
Step 2: Move the knob back to the 0.0 position and lock the knob by pressing the lock lever down, as seen in figure 4.
Step 3: lay the MPPI-2 on its back to expose the bottom of the knob. Insert the .9mm Allen wrench into the knob set screw and turn counter clockwise a few turns to loosen it, see figure 5. The set screw needs to be loose but does not need to be removed to lift off the knob, as seen in figure 7. Note the key tab on the knob and the key disc on the potentiometer .The key disc on the potentiometer should be at the 9:00 position. If it is not it you will have to loosen the ½” nut and rotate the disc to the 9:00 position and retighten the ½” nut.
Step 4: With the knob off rotate the shaft of the potentiometer counter clockwise till the shaft stops turning. Gently slip the knob on the shaft with the number window at the 2:00 position, see figure 8. Carefully rotate the knob counter clockwise from the 2:00 position to the 12:00 position until you feel the key tab fall into the key disc hole. Retighten the .9mm Allen set screw into the knob. Be careful to not strip out the set screw but get it tight enough to keep it from slipping. Now unlock the locking lever and check that the rotation of the knob goes from 0 to 10 and back and does not exceed 10. The unit is now ready to reconnect and test. On some older units the keeper ring is a metal keeper ring with an upright tab, but the procedure is the same.
If these steps don’t correct the Pulse Duration Knob contact ASI for further instructions on this unit.