I developed a warp in mine. I found a couple pieces of plywood large enough for my mat to fit between. I misted the mat with warm water. Just a little. I put the mat between that and the plywood then some heavy bins on top and left sit overnight. Worked for me. Good luck. Depending how old it is, you might consider a new one. But I'm all about saving money too! Mine is 10 years I think. She still has some life.