I have a cheap-o board I am going to fix the plastic slick on the bottom with a tube of Liquid Nails - Interior Exterior Extreme Heavy Duty Construction Adhesive.
I will write back in a couple of weeks.
Also, if it is just the rails on the side or a ding in the bottom slick - Eboadyboarding.com recommends just hot glue. https://www.youtube.com/watch?time_continue=182&v=93Dz2nnYZKc&feature=emb_title