Trailer suspension sag?

You may have broken leaf springs. Not uncommon. Also the bushings wear out very quickly. Wet bolt kits that replace the bushings with bronze bushings that can be greased through the bolts are pretty cheap and you can have your springs re-tensioned when you take it apart to replace the bushings. New springs are cheap as well.

Should not. Sag is a function of weak springs. So sag equals low grade components to me. My 11 year old fiver still sits level with two slides on the street side.