I get a treadmill it’s got some years on it but still works fine for my purposes. Long ago it got some rain in which God and of the back part of the deck and down in the particleboard that they use for decking. So it’s swelled and I ended up making a new one out of three-quarter inch plywood and a number of coats of Enamel paint. It worked fine except for it’s a little too Flexy and it makes it Creak ( steel side frames)which has irritated me for a long enough. So considering the constraints of space I have a little bit more I can’t use without the belt binding, what’s the best idea that take the flex out of that deck without greatly thickening it. I’d say I have about 1/2 to work with +- What I don’t want is more particleboard and Formica if I can help it. Thanks.