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I looked up the 000G52-06-05B. The description is:
SCREW - MACHINE - 6-32 X 5/16 PTH - ZINC
You should be able to find 6-32 screws from a number of sources. If you have an ACE Hardware near you with a large Hillman hardware aisle, try there first. If you want to order online, one of my favorite sources is Bolt Depot. A link to their zinc-plated 6-32 Phillips pan-head machine screw listing is
here. Part number 9226 is the 5/16-inch version, selling for 8 cents each. If you want to reduce the chances of rust, pick the 18-8 (link
here) or 316 (link
here) stainless versions.
I'm guessing, but the 000G52-06-04B part number may be 1/4-inch long.
At the prices listed for Bolt Depot, you can keep a range of screw lengths and diameters on hand.