To level a trailer home, remote the skirting, check the central beam position, correct the position with a jack, insert shims, and replace the skirting. This task requires a 6-foot carpentry level, shims, a jack, a hammer and a flashlight.
Put on heavy work gloves and eye protection. Remove the trailer home's skirting, and set it aside. Locate the central beam, and hold a 6-foot level up to the middle of it. Note the location of the indicator bubble. Crawl along the beam toward one end of the trailer, stopping at every beam support to apply the level. When you reach the end of the trailer, return to the middle of the central beam, and repeat the measurements on the other side. Note which portions of the beam are not level.
Place a jack beneath one uneven portion, and raise the jack until the beam reaches proper alignment. Verify the alignment with the level, and then wedge a shim in the gap between the beam and support. Tap the shim into position with a hammer, and then release the jack. Repeat this process at all uneven areas.
Use a flashlight to inspect the water and electrical lines near the central beam, note any portions that were damaged during leveling, and then replace the trailer home's skirting.