I had some success at the hardware store so I figured I'd share.
I took one of the screws in to match. I couldn't get the exact length. Ones shown are a little long hence the washers. Took two washers to even them up but it works.
#4 X 3/8 inch screws with #4 washers.
The cart slot flap seems to use same type of screws but even shorter. Probably need to use 5 or 6 washers to get that situation to work.
Anyway hope this info helps someone.