Check probes against a known reference on a fixed day each month, and write the check down even when nothing has drifted. A probe that is never checked is one you will eventually argue with.
Four failures hide behind a tidy screen. A value that has not moved for hours is usually a dead channel, not a stable tunnel. A jump of several degrees in a minute is usually a loose connection. A wet or bent probe reads its own condition. A probe moved at unloading and never relabelled reports the wrong end forever.