Mine has a small lever to turn from being in a "locking" position, raise the leg (by pulling then folding back), then push down in the middle of the table. Sometimes it takes a fair amount of force to push it down.
Bringing it up is easier. Pull up, set down the leg, lock the lever in place.
+1 4AggiesMom. We have the same trailer and had my parents with us the last time out so we utilized all of the beds including the dinette. Rotate (unlock) the small handle that is near where the standing leg connects to the table. Locked, the handle is pointing to the front of the rig, unlocked is pointing to the rear. Then fold the single standing leg up. Then put some hefty pressure on the table between the middle and where it reaches the wall. It can take some force to get moving but once it's gliding down you can ease off! I would recommend lifting up the seat cushions 1st as the ledge that the table will come to rest on is covered by them otherwise!