There isn't any real adjustment to a torsion axle. Basically, it is some rubber rods inside the steel tube with the swing part of the axle shoved in while the rods were kept very cold to shrink them. See if you can find an axle tag with the manufacturer and number on it. There are specs for the axle (somewhere) that would include the loaded ride height and the drop unloaded.
I am very familiar with Airstream torsion axles, and I would guess that yours would be similar.
If they are the same you should have a downward tip to the arm with the trailer unloaded, and they should be even or slightly down when fully loaded. If they are negative (tip up) then they are overloaded or weak. If they don't drop at all when you lift the wheel off the ground then they are toast.
I actually prefer the torsion suspension for trailers, it gives a great ride and keeps the ride height lower, which makes for a stable tow and reduces the number of steps to get into the unit.
Aaron