Call the company. Best bet. Then you can get the exact thread size you need, and then head over to McMaster-Carr and order some screws. Small stuff like that is probably going to come in a bag or box of 100, so you will lots of extras. For some reason, #6-48 sticks in my head, that or some goofy metric size. Probably metric. Maybe M3 with some super fine thread. But I digress, call company, they should be able to crank out that information over the phone.