If I remember correctly, there a very tiny metalic fibers used in the catalytic membrane used in these irons, and they can be fragile. Rough handling will damage the membrane, and not enough material is left to efficiently / easily start the catalytic action. Preheating with the hairdrier gives it a chance to catch.
Butane curling irons suffer the same fate. Couple of drops on the bathroom counter and you get to buy a new one. My wife had 2, one was a "travel" unit, that went on the road, lasted about 6 months. The other, same model, lasted over 5 years, it never left the house.
edit -- if yours has the "burner" in the tip housing, changing the tip will solve the problem, if not, new iron is next. The weller portasols are pretty good, long track record, easy to find parts.