That is just a Ranco controller isn't it? If so, I think the probe length is closer to 2" long. If it looks broken off, I would make sure part of it isn't still in the well. A 1/4" drill bit should work to clean it out. Just make sure you don't drill through the end of the well.
If there was a chunk of it stuck in the well, I would give it a try with it cleaned out before ordering a new one. Also, if there was no silicone around the wire, that would help make it read more accurate.