Recently I bought a nice little travel iron, at a thrift shop. When I got it home and tried to use it I realized that it had a sticky area on the sole plate. I tried every thing that I've ever used for stickiness and nothing worked. Finally, I did some looking around on the internet and found my solution.
I sprinkled salt on a brown paper bag and ironed back and forth, back and forth (with the iron turned on) over the salt until the stickiness was gone. It worked great!! Maybe this will help your problem, too.