I've been joining in the debate on the Machine Knitting e-list about waxing your yarn while (or before) knitting.
Here is my two cents worth.
I've been doing this for over 20 years when someone showed me how to attache candle stubs to my tension arm for my knitting yarn to run over.
These two pics show how I attach the candle stubs with a rubber band. Eventually the candle stub wears lots of grooves and wears through, the rubber band gives up the ghost too, but they are so easy to replace! I've loved this method for so long I forgot there were commercial waxers.
I've noticed that when I don't have wax in place or the yarn has slipped off my knitting is a bit rougher, you can just feel it in the carriage, so I pop the yarn back onto the wax.
Knitting as I do for a living I have to save where I can, this is small but significant..... more money to spend on yarn!