Sounds like the barb connectors inside the tube have rusted out. You can buy these at a bike shop. Having said that I just fixed mine that was loose because the connectors were rusted out with 2 (3)in ss bolts and a threaded connector. I removed the old rusted barb connector and bolt put one SS bolt in from the backside of the flange that attaches to MH then threaded the connector to it, slid this inside the tube then threaded the other bolt through the ladder vertical post and into the connector inside the tube. Once tight I screwed the flange back to the MH with over size screws. This fix is much stronger than the original design and will not rust out.