I have an incandescent 3 way GE Revel bulb. It can do 50-100-150w cycles. I used to be able to use it at all cycles (usually used 100w) but now I can only get it to do 50w. When the problem started to occur, I could screw it in tight and they would all work however nothing works now. 50w is the only cycle that works. If you shake the bulb, it sounds as if the wires have snapped. Are there two (or three) filaments in three way bulbs proving this to be the norm for the way three way bulbs work?