I found an easy way to test piston squirters. A Sharpie marker has just the right diameter and taper to (mostly) block off the oil passages and allow you to use an air gun to test the squirters.
Passenger side case half: Insert the sharpie to block off the passages inside the case bolt bore. Then use your air gun on the main bearing oil hole. I filled things up with brake cleaner and then applied pressure to give a visual of the squirter opening. The oil squirter passage intersects the passage from the case bolt bore to the bearing. The Sharpie blocks off the case bolt side of this passage so all the air goes to the squirter.
Drivers side case half: This one is much easier. The squirter oil hole is visible right at the top of the case bolt bore. The Sharpie is just used to block off the outer side of the case bolt bore. Then you just need to apply air pressure to the top of the inter case bolt bore.
