The cash drawer is usually the most reliable part of a complete POS system, which is interesting when you consider the ancient technology used to build them.
Some drawers have weak note clips - ensure adequate strength.
If the clip is plastic, this does not necessarily mean the clip will break under normally expected workloads. Draw slides and rollers. Ensure the drawer does not have excessive sideways wobble, particularly when loaded with coins. Sometimes rollers can fail, but we find this is very rare. The drawer stop.