1. make your own screen
2. ask a headshop how to help or if they have new screens
3. buy a new grinder- the 4 chamber bob marley ones are only $20 and ive had mine for a year. i can make kief with my nuggets by hand and it collects good overall.
4. gas station
EDIT: PM sent. also, look up that bob marley grinder cuz it really is a good investment. if you want when i get home to baltimore tonight i can PM a pic of mine with the piece taken apart and the kief that will take me 5 mins to make with my new batch of nuggets.
CH is right, sourcing is sourcing is sourcing. We can't give you a direct place, but I think 'contact your local headshop or look online' is pretty damn good advice.