Your right the last few days have been a little nasty for outdoor truck recreation. As an ex-bodyman the problem usually lies in the hinge or the aligmnet of the core support. Find a nice level area and do as Mike did. I have even seen these things have a sagged rail on one side not a bad fix but you need the facilities. Measure each side from the lower edge of the rail to the ground. Then from the bottom of the support to the ground. Keep moving up, if this is were your problem lies it will be found quickly. If it's in the hinge try taking off the hinge and reseting the pins at the pivot points by placing them on an anvil or other steel surface and using a large hammer peen the end of the pins to tighten them. This is not a permanent fix but will work until a replacment can be foound.Enjoy the Beautiful B.C. weather it soon will be Spring and our Eastern neighbours will still be shivering.