If Danny's suggestion fails, but you are able to identify the stud (I can't remember off hand what the specs are), check

http://www.mcmaster.com/

a quick search for "threaded stud" says they've got 3,677 different styles; they'll likely have the one you need (somtimes things come one at a time, but more often, for somthing like this it'd come in a pack of 5 or 10).

Also, you can get a set of extra tough studs (Grade 8) while you're at it, so you don't run into this problem again (still use the grease, of course).