This installs inside the black auto index clamp on the steel ram. The square black ratchet rides on the 1/4"x 1/4" steel index rod. When removing the aluminum turret, be sure to raise the ram to disengage the square ratchet from the twisted part of the rod.
The nylon square ratchet that comes with the turret press is designed to properly index the press for 10s of thousands of rounds. This inexpensive part is made of nylon for two reasons with the first being that if the index rod is operated against the proper rotation, the nylon will fail before any damage occurs to any other part. The second is that they are inexpensive to produce and purchase.
The ratchet enables the indexing without "tweaking" or adjustment. The index rod may be removed and replaced at will without affecting the timing of the press. In the unlikely event that your press was received and not indexing correctly, the ratchet is not the reason and the issue is easily resolved by turret press index alignment. Here is a video showing how to align the turret--
Youtube - Lee Turret Press Index Rod Adjustment
The only reason the ratchet would be damaged is from forcing the index rod against that ratchet. This generally occurs when turrets are removed with the ram at the bottom of the stroke as the ratchet is engaged during the down stroke. When removing turrets, it is necessary to raise the ram about an inch or so.
A problem can ultimately affect indexing if the ratchet is excessively forced against the index rod, because the top portion of the ram, designed to rotate for another reason, would do so under these circumstances. Then, even with the ratchet replaced, the entire housing is off center. The proper alignment of the housing is completed by using the lever portion of the priming arm and aligning it with the two bumps on the base of the press
The nylon housing that holds the ratchet never needs to be opened other than to eventually replace the nylon ratchet. Remove the index rod, then the housing by removing the horizontal screw. Replace the ratchet remembering to place the flange in the downward position and reattach the nylon housing. This housing does nothing more than contain the ratchet. Do not over tighten the screw because the threads can be stripped.
