Margaret if the control unit behind your two rotary knobs is made by Hytec Model 3360D I can repair it for you for £12 + Return postage. I have repaired many of these units, sometimes when they blow there can be several parts gone. They are not obtainable new except from a company who say the minimum order quantity is 3500 costing £25 ea and several parts can only be imported from China but I have all parts required to do the repairs. To repair you need an electric drill, 7 mm bit, soldering iron, solder and a replacement pop rivet
Paul, December 2014