I had the same problem on another TT we owned. I eventually went to Lowes or maybe it was Home Depot but I found some brackets in the cabinet drawer section that appeared to be very similar. I replaced the broken ones and they did not break again, well at least not before we traded it in on our 2010 Jayco 32RLS.
2010 Jayco 32RLS
2006 Expedition King Ranch 5.4L
The drawer supports at the rear of the drawers in the kitchen let go and the drawers wouldn't operate. Instead of the factory staples I removed the drawers and screwed and glued the entire assembly. Took about an hour and should not be a problem again. The assembly can be seen if you remove any of the drawers.