Convection oven was baking unevenly
Our convection oven had started browning everything on one side. The technician tested the elements, replaced the fan motor and recalibrated the thermostat, then had us bake off a tray before he left so we could see it was right. Parts for our model were not on the van, so it took a second visit — he told us that up front, and the return trip was quick. It bakes evenly now.