The XXX4 belt is actually easier to get. It's the same as the XXXS Black "long" belt so it requires the appropriate tensioner. That may be your problem. You're using the longer belt with the stock tensioner which doesn't allow enough travel.
Here's a pic
http://www.wholesaletrains.com/Detail.asp?ID=200813315
Last edited by Evoracer; 06-01-2012 at 02:49 PM.