C/S Oil Furnace. Took temperature rise. Replaced oil nozzle and strainer, no oil filter. Washable filters are clean. Checked transformer, cleaned electrodes, tested blower motor, bled air from oil line. Took combustion reading. Unit would not shut off with thermostat would only turn off when pulling one leg of tt off the primary, diagnosed with Kurt and during trial and error primary burnt out, replaced primary, and made new wire at thermostat specifically for rc and rh after retiring unit heat will not come on and shut down with thermostat, tested ac as well to make sure ac would come on and off. Unit running normally.