1) be sure the tower is level (both ways)
2) be sure the pin of the rotating lens that rests in the dimple of the bulb is clean and straight - and somewhat "sharp" - to reduce drag as it turns.
3) the trick is all in the little "fins" or vanes in the top of the rotating lens. It is the hot air rising from the bulb through these fins that makes the lens turn. They usually need to be fine tuned. They want to be bent upwards at the right angle - too much angle and the hot air escapes without turning it. Too little and the hot air cannot escape in a good enough stream to turn it. Keep varying them and trying.
4) match your transformer accessory voltage to this beacon with the voltage of the bulb you are using. You want the bulb to get good and hot, but if too hot (18v with a 12 or 14v bulb?) it may actually soften (melt) the plastic pin that rests in the dimple, which will increase drag.
overall it is finicky no matter what, which is why they switched to making the vibrating one a few years later, which is also finicky and unreliable. primitive technology.
