RE: Footstrap broken screw
An important direction to enterain would be a new insert. Of course, you must resolve your current problem by removal, but a new foundation will resolve everything. If you're happy with a single position, you can establish a two position attachment that will be fairly bulletproof for the future. The plastic stuff that you're faced with now, especially if the remaining screw component is impossible to remove, may very well be history. Still no problem, particularly if you follow restorative instructions and procedures as available in the following website.
Really, it's good stuff to know, and pretty simple to accomplish with a minimum of tools. I like working with composite materials, especially since a lot of trick stuff can be done with these materials that no one is leveraging off of. Imaginative ideas can really take off if you take advantage of opportunities. A great resourse base for more than just windsurfing or surfing stuff.