Oops. Posted in appliance by mistake. Package unit blew transformer. Found bare thermostat rubbing against case. Repaired, checked coil on contactor and the defrost board is good. Fried the new transformer. What am I missing?

Something is still shorted out. Before you damage another transformer I suggest you install a in line fuse on the transformer. This way you can track down the problem and if the fuse blows you will know you have not found the problem yet. Fuses are a lot cheaper than transformers.