wiper arm screws

[c20pickup]

could someone tell me the correct screws that belong in the cowl to hold the wiper shaft that connects to the arm. there should be 4 of them. i figured its a #10 screw with a #8 head. problem is used a 1" screw and it binds up on the offset metal bracket for the arm so the motor cant make its full swing. i realize a shorter screw is supposed to be there but the offset piece is so close to the bottom of that hole i don't believe it would have much if any holding power. i hope this rambling made sense.... thanks in advance