We've tried and compared several types of refractometers over the years and have settled on using the Misco units. We've had at least a dozen of them. They get a lot of use in our research - sometimes hundreds of measurements daily...mostly for sap, but occasionally for syrup. Most are them have proved to be very reliable and have lasted for years. We had one unit that failed within a single season (bad seal we think) and another that failed within a couple of years (probably also a bad seal). Given the amount and conditions of they are used in, they do get dropped occasionally, so we've not sent them in for evaluation and repair. It's a tough life for an electronic device...very cold or very hot temperatures, liquids, high humidity (sugarhouse), in the lab, in the woods, in the sugarhouse.

This situation sounds unusual and I hope you're able to get it resolved.