Two-versions of Weber 40 IDA 3C Carburetors Delivery Valves

[auto*legends]

Each Weber 40 IDA 3C carburetor has three Delivery Valves: Weber part number 64290.005, item 71 in the Weber exploded view drawing. It’s the brass check valve that holds the Pump Jet item 71 (squirter) in place.

I recently removed both carbs for rebuild, but decided to do them one at a time. I disassembled the first carb and subsequently soaked and cleaned everything. I was checking parts for assembly when I noticed that one of the Delivery Valves didn’t have the little check ball inside it. I discussed the finding with a few friends, and consulted with some experts. It was easy to conclude that the part must have been defective, so I ordered a few new ones from the Oil Analysis Company. The Oil Analysis Company is a retailer/distributor of PMO Weber stuff. BTW, I have had great success when dealing with both of these companies.
Anyway, I then decided to disassemble the second carb prior to assembly of the first one and guess what? The center Delivery Valve didn’t have the check ball either. Maybe everyone already knows this, but I have looked and can’t find it documented anywhere.

Thoughts? Comments?

[1QuickS]

What are the odds of that?

Squirter bolts changed design over the years, the earlier ones had a smaller waist diameter with four holes and the later ones had a larger waist with two holes; the later ones are more resistant to permanent distortion with subsequent cracking due to over-torquing. Another minor revision to the larger waist squirter bolts is a counterbored recess in the top. All have lead plugs in the top, recessed below the screw driver slot for retention of the check ball. I repeen these lead plugs to be sure they don't rattle out leaving the steel ball to be ingested by the engine...definition of a bad thing.