Be very careful if using someone to help you. Do not have anyone under the trailer. I just retired as a firefighter and about 20 years ago responded to an incident where a driver from St. Johnsbury was on the dead end road outside the terminal with sliders that wouldn't slide. He got under the trailer to hold a lever while the terminal manager got into tghe truck. Instead of the truck going forward the man behind the wheel put it in reverse and the driver's head was pinned between the trailer cross member and the slider tandem and killed him instantly. The terminal manager did not have a license to operate the semi and because the truck was on a highway was charged with illegal operation and the company paid a BIG settlement to the widow.