First my stove had trouble responding to the wall thermostat but worked fine with switch on stove. Today the switch on the stove would not work. Fiddling around I turned off the pilot and tried to relight. Igniter sparked for awhile when pushed but now no spark. Seems like I now have multiple problems, any advice is greatly appreciated. The stove is approximately 15 years old and has never had a problem although the pilot flame does seem to have been getting longer and more yellow. Thank you.