It is obvious that you should clean your iron every now and then, right? I use wax cleaner occasionally, with some paper towels and remove some of the wax on the sides. With a plastic scraper, I also remove the big blobs of wax formed on the bottom.
Done? I thought so, too, until reading some more on the internet: I read about using sandpaper... and after having just done that, the results really make a big difference.
Examining the base of the iron more carefully, I found some deposits that I couldn't remove with my fingernails - probably old burned wax or something... Also, scratches and stuff - the iron looked like I could use a new one... an attractive proposition always, if it wasn't for the cost.
Time to mess with it and experiment!
I used first some scouring pads (from the dollar store) that I use, but it was going very slow. I moved to some 150 grit aluminum-oxide sandpaper and then down to 100.
So, the sequence that worked for me was:
Done - time to grab another beer and admire your spanking new waxing iron! Do hot scrape some crappy skis with it now, to completely remove the metal shavings whatnot.