Trouble with a heil furnace
 

i have a heil furnace that started to act up the vent motor starts to run but does not lite off sometimes i go down to the furnace and tap on gas valve and the ignitor starts to glow red and lites off then runs a complete cycle someimes it relites and sometimes i have to tap on gas valve any ideas this unit has a honeywell sv9500m smart valve in it thanks mike

there was a smart valve that was notorius for a weak connection in the gas valve since when you tap on it and it starts, I would change out smart valve