Surprised no one has brough this up yet...

Do a search on this site. There is a guy (I think he owns Arriba) that will repair them. All reports I've read have been positive.

Every time mine have been stuck, I've been able to take them into the water (at least knee-deep) and submerge the whole thing and just keep working it until it breaks free. Once it breaks free, go into deeper water (to be sure you're not taking in any more sand) and keep working it to get all the sand out that you can. Following up with a hose and soap is also a good idea.

Good luck.

Mike