here's whatcha do
ok so... you'll need to get that puppy out. vice grips are the weapon of choice. It used to be a "thumb screw" as you have noted with the plastic head that's broken off. In that same vein, its already broken, so breaking it more is acceptable. you'll have to crank on it pretty hard with the vice grips to get them to hold. it will deform the end they grip significantly, but we're not worrying about that. use a good penitrating oil during the extraction. i'd stay away from WD-40 and go strait to a little something i like to call PB Blaster. its real, you can buy it, and its great stuff for this type of thing and many others. with any luck, the screw just threads out. however, you mentioned that it doesnt seem to move easily. this is disconcerting because it probably means there is some problem with the threads... gualling or crossthreading. we'll cross that bridge when we come to it. if it threads out, just bring it to your local hardware store and pick out your favorite stainless (or aluminum if you want) screw. go with the largest size head you can find or you may need a washer. you could get fancy and buy a wingnut to put on your replacement fastener whitch would make it "tools free" if you were so inclined. all you have to do is bring in the old deformed stump and match the threads. if the threads are still decent you could find a nut that threads on to it and find the size that way. be ware of metric and loose fits. the correct size will work just nice. thread size guages work very well also. now, if you cant get the screw out, you'll have to grind it down flush to the mast (dremel tool or just a metal file) then you'll have to drill it out. then you'll have to recut the female threads with a tap. this will be larger than origional. same thing if the threads are crossed or gaulled. then you'll have to buy a new fastener with the thread size of your tap. now this is all assuming that you still have the mast gate plate portion of the setup. if not, a whole new kit can be purchased for boku bucks from rigrite.com
