First of all, have you changed the globe? Second there could be a loose/bad connection at the lamp holders, starter holder or ballast. Also check the ballast, it may have a voltage printed on it. The starters job is to simply create a circuit through the two filaments of the tube on start up until the tube strikes and then goes open circuit to allow current to flow through the tube. If there is not enough gas in the tube it just keeps trying to strike, hence the annoying flashing syndrome.
