Shoebox repair question (likely easy to answer)

My Shoebox was running and made a loud noise. "****e! That the end of her" I thought.

Fortunately, it was only the flat bar that connect the two doohickeys, kinda like you see on train wheels (see picture one). It drives the pistons. It had fallen off completely and was laying loose inside the compressor.

Laying inside the case were two round doohickeys with slots on them(see picture 2). These had held that connecting rod in place for years but apparently they're too worn out to continue their job. One of them is pretty dang loose.

I suppose I only need new round doohickeys to hold it in place. Does anyone know what they're called? Does anyone know where I'd get them at? Does anyone have suggestions for a better repair using some other type of doohickey?

Well, I guess I could read the manual, couldn't I? I'll go do that now, but I'll still need to know where to buy those round things I suppose.

Thanks. I appreciate ya'll.

Picture 1
https://drive.google.com/file/d/1Tix...ew?usp=sharing

Picture 2
https://drive.google.com/file/d/1Tu2...usp=drive_link

Tom built the Shoebox from W.W.Grainger (I think) catalog so that the parts would always be available. Contact Beemer with questions. he probably assembled most of these.

Pic #2 it's called a Speednut , A Good Ace Hrdw should have'em

What is the shoebox?

It is a small compressor used to fill up tanks. It is capable of 4,000+ psi fills made and sold by Tom Kaye.

Oh nice! Ive been doing my own fill station thing for a while now since there are no fields/stores near me anymore and we’ve started playing in my woods. I’d love to have something like this. Are any of them ever still available? Do they ever come up for sale anywhere?