Alright, how about a little secret from Truck Town Thunder. There are two different places we get polycord.
1. McMaster-Carr A little more choice in color. Seems to have a smooth surface.
or
2.
/ - Doesn't seem to have a choice other than green but the Polycord has a rough surface that help the balls move up an down.
We haven't had any problems melting either one. We have used soldering irons, heat guns. The best method we have found is using a soldering gun with a special tip that is flat. It seems to work the best that we have found. Something sort of like this:
http://www.google.com/products/catal...CIkBEPMCMAE4Hg