I had the same problem with mine. I fixed the problem with fibreglass matting. In my case the center portion of the headliner was caving in. What I did was I placed a cement block on the floor and placed the low spot of the headliner on the block making sure the headliner was completely off the ground. I then put weights on the headliner on different locations until the headliner had the right shape. Then started laying boat fiberglass matting on the headboard where it had been out of shape. I let it sit for a couple of days then removed the weights and gave it another coat of matting this time going wider as the weights were no longer in the way. This worked great for me.