Bought this in 2000, use it daily. I did find that the readings would fluctuate some when i put any strain or stress on the cable going into the probe, or where the plug goes into the back of the meter. It seems just the smallest movement of the cable could change the reading so,,,,,,,i used GOOP to secure the plug so it can not move while dangling the cable/probe. I also used goop where the cable and probe meet to secure the cable from being twisted or moved slightly. Its been dead on for calibration for years since i eliminated any possible movement of the cable and plug.

I suppose all meters have their own little tips/tricks to keep them in top condition. I aslo find the tip will dry out after a few days. Its easy to just soak it in the nutes until it steadies out. Mine didnt come with a sponge in the cap either, but a wad of paper towel stuffed in there will work also.