try using a thin sewing needle to clear it. Poke it clear with the needle (remember you are trying to clear it not open it up), if that doesnt work use an air canister (http://cgi.ebay.co.uk/AIR-IN-A-CAN-COMPRESSED-AIR-DUSTER-CLEANER-400ml_W0QQitemZ370026952231QQihZ024QQcategoryZ162QQssPageNameZWDVWQQrdZ1QQcmdZViewItem) to blow it clear. You'll normally need to lift the bonnet and blow air from where the water normally squirts into the jets, thus disconncting the washer pipes temporarily will be necessary. Hope that makes sense.
I haven't done this with a supra but it should work.