I have a carrier natural gas furnace, model no. 58es080-30. The pilot light ignites, then you can hear a clicking noise, after about 15-20 seconds the blower fan starts up but the main burners are not lit. The furnace has acted like it's been having trouble igniting in the past few weeks, seems like sometimes you could hear the clicking noise 7-8 times before the main burners would ignite, now I have nothing burning but the pilot. Any suggestions would be apperciated. Thanks.