I don't know anything about the fan motor but you also might not have to replace it with the exact same motor if you can find something similar with the some voltage/wattage input and RPM's or higher you should be okay. I would try disassembling and seeing if it's just gunked up on the inside or has a bad connection somewhere.
The kegerator has been on the back burner because I've been really busy with work. When I'm not working I've been reading up on your electric build.
That fan is perfect! I'm going to go ahead and get it. Thanks for finding it!! I'll update when it gets here.