The stem must operate repeatedly and consistently under very high compressive loads. It is essential therefore that it remains in complete alignment throughout the length of its stroke. The alignment should be checked weekly.
Because of the high pressures carried by the stem, it is essential that the load be uniformly applied. Uneven loading will eventually cause bending or breaking. This can result from a variety of reasons such as improper installation, distorted pressure plate, misaligned press, jammed butts (causing the container to shift), or improperly cut billets.
As noted above, care must be taken to avoid these situations as the stem can break catastrophically.