If that dehydrator was commercially built, you may be able to find a book or at least some information with a Google search. If I had access to it, I could use a clamp-on ammeter and check the current draw and tell if the heating element was drawing what the nameplate said it should. There is another way to do it, but it is pretty involved and that is by watching the electric meter with only the dehydrator operating. That is impractical though. If it has a temperature control (thermostat) on it though, put a thermometer in it and check to see if it will hold that temperature. If it does, the elements are working the way they should. I thought I would like a larger dehydrator, but I am glad that I don't. It took me 5 hours of processing those apples I put in there yesterday. If I had a larger dehydratyor, I probably wouldn't even bother to start.