Problem with slideout

Hi, we have an arctic fox 990 truck camper 2007, secondhand for 2 years. We just got back from an 11 week trip to the canadian west and all the way up the Dempster highway to the arctic océan. Towards the last 3 weeks of the trip we notices our slideout not going in properly. It goes in more than needed at the bottom and leaves à gap at the top of à good half inch. The 2 sites on bottom are even and the 2 sites on top also. It's as if the top is out more and the bottom more in. 

Is this just a slideout ajustement? If yes what do we do?