Strange gear cover screws

I try to complete WLA motor cases. I have a problem with screws in gear cover. Part List shows that for relief pipe there should be 10-32x1/2" (catalog number 036) and for shaft timer 12-24x7/8" (part number 044). When I try screw this sizes it does not fit! For timer shaft ideal are 10-32 and for relief pipe I can't figure out. What sizes of these screws do you have? Is there a mistake in parts catalog (TM-10-1482)? If there would fit bigger screws that these supposed to be I would think that somebody increased size because destroyed thread. But in my case there fit smaller size! (sorry for my english, I'm Polish).

Piotr, POLAND

[Pa]

My book calls for timer mounting screws as 042A., 12-24NC x 1/2". And for relief pipe, 036, 10-32NF x 1/2".

So, your book says the same what mine. But it still does not explain why these sizes do to fit in holes in my gear cover.

Piotra, Is it possible someone has installed a helicoil or some other thread insert in order to use screws availableto them?