Just wanted to chime in ad thank everyone for this thread! Took our first trip in our new 2014 Grey Wolf 26bh over Labor Day weekend. Got home, and a few days later went into the camper and it smelled like a litter box. Traced the smell back to the rear of the toilet. Thinking there was some kind of venting problem, I came online to research the problem, and found this thread. That was on Friday night. Called Dometic today, spoke to Heidi, and a new 310 will be delivered tomorrow! Just needed the serial number from the loo. Surprisingly she didn't want the stinky one back, said it could be recycled.
For what it's worth, our trailer was manufactured in March 2013, so hopefully they're not still putting this model toilet in new campers...