Problem: Snuggles either stops working or begins barking incessantly. This is apparently a very common issue, and also one that most parents dread - a broken toy on Christmas morning.
Cause: Snuggles has a loose battery connection, somewhere. This is causing the puppy to either not work, or reboot over and over. The constant rebooting is the cause of the incessant barking - it is replaying the startup bark over and over.
1. Try removing the gaskets in the battery holders. They look like this:
These are normally separate parts and are not glued into place or anything. Just pull them out with your fingernail.
The gaskets really don't have any function in Snuggles. They theoretically seal the batteries against water, but this should not make any difference since Snuggles is not a water toy.
Once this is done, reinstall the paws (battery covers) as normal. They should be able to press down on the batteries more effectively and will (hopefully) solve the connection issue.
2. There is a video on the subject that shows how some Snuggles - likely earlier ones, though that is just conjecture on my part - have a loose cap on the battery compartment in the left-hand leg. Repairing the cap requires removing the battery holder from the leg, which takes a bit of doing.
I removed mine and found that the battery holder was already fully glued, with no possibility of disassembling and regluing it. So that did not work for me. I did not try the right leg because I felt that it was unlikely that one leg was glued properly and the other not.
One way you (should) be able to tell if the video will work out is if Snuggles starts to behave when you push the battery holder together with your fingers. If so, the internal endcap is likely loose and can / should be fixed. If not, that is not likely to be the problem, and you might want to look for another solution before removing the compartment from the leg.
For what it's worth, removing the compartment from the leg is not too hard and is easy to reverse, so you're not risking much by trying it. But it may be unnecessary since it takes only 10 seconds to remove the battery holder gaskets.