As said, its pretty standard that they slump somewhat.
For some reason, they don't have a lock for stabilizers, so I chain the pads to each other in the up positionif I'm planning to not use the backhoe for a few days. It not only saves time when you want to use the hoe or tractor, it means you don't accidentally whack something with a slumping stabilizer.
It particularly useful to do this when you detach and store the backhoe on a dolly (which I recommend whole heartedly.