When you have a mobile home that's been sitting on the same lot for several years the soil may begin to settle. This can lead to important parts of the house not being supported, leading to sagging and dangerous structural problems. If you notice these problems you can get a mobile-home jack to push the unsupported sections up again and to hold the shape of the house.
Get underneath the mobile home and find the area that's not supported. You'll be looking for an I beam or other structural support which is sagging. If there is clearance between the support and the pylon that's supposed to be holding it up, that's where the problem lies.
Place support blocks further along the sagging beam so that you have a small, sturdy platform. Place your mobile-home jack onto the blocks and jack up the house until it's level again. Check the doors and windows to make sure that they open and close properly, since that means the house is level.
Place large wedges between the top of the support column and the edge of the beam until the beam is once more supported fully. Secure these wedges with screws. Gently let the jack down so that the house's weight can settle down onto its new support. You may have to do this with more than one support if there's been a large change in the soil, but the process will be the same for each support pylon.