We had a 95 Viking where the lift system malfunctioned. If yours is anything like the one we had you gain access to the lift cables by the back bunk I would guess a bad
lift cable. this was a real probem. The cables become tangled. first Cut four 2X2' to
the raised roof hight, Bungie them to the Posts. Now that all the tension is off the cables carefully untangle them if a cable is broken contact Viking direct for a replacement set. They replace fairly easily. If you do not have an Air Conditoner on
your roof the roof will lift fairly easily once you have made repairs carefully crank down the roof. Before we traded ours in anytime we used it while the roof was up
and supported we would make sure that all the cables were not tangled. Hope this gives you a starting point.
Pete & Elaine