Which truck is it? Generally the 1st answer is yes, but use the lowest gears. Turning the wheels too, will help break the suction of the mud/whatever. Use extreme care though. You are using lots of power, and its real easy to break something. Get the winch line tight first. Always keep tension on the winch line, and never let it get an axxhole in it, (that's a loop, for non believers) or you can kink it.
Don't know the truck you have so its hard to answer the 2nd part, but sometimes if you let the winds on the drum get loose, and then you put a heavy pull on it, the line will cut down in the wraps and pinch itself. If this happens, you probably can't pull it out manually. but need to tie onto a good tree, and pull it out under power with the truck. Its a bad thing to let happen. The line is expensive, and needs to be taker very good care of. Always keep drum wound tight!
