Going out on a limb posting this - hopefully it's educational. Most folks are probably going to have to deal with it at least once, so this might help take the edge off. There is a speed bag in motion, and rumor has it that makes it eligible - although without the music, it's pretty silly. So am I.

These guys couldn't resist a little play on the bag, and were very polite about expressing their interest. It really is an irresistible piece of furniture.

Have a chuckle on me.
Measure twice, cut once - written dimensions frequently lie.
See YouTube comments for a link to a more thorough step-by-step video by Ron Hazelton.