I have a 1956 United Handicap and could not find any pins either.
Mine are mounted to a round pin held on by 2 E-clips.
I would love that coin return piece. I wonder if you could get a close up photo ?
Also, What is the O.D. of your puck ? I have heard there were different sizes, but there is very little information as to what those actual sizes were. I did not think so, but after I finished the restoration, it gets a lot of play.
GOOD LUCK and ENJOY.

Yep, those are the pins!

I call it the foul line bar. You notice it's right above the foul line on the playfield. I think it was to stop your hand going past the foul line = no cheating.

The bar near the front of the pins was actually the lead edge of a piece of plexiglass that covered the switches. Protected the pins, maybe, but I think it was another anti cheat device so you could'nt trip the switches manually.

The last piece to the puzzle is the pin surround/protector. It was an integral part of the assembly and prevented the dreaded pin assembly droop you see on so many of these old games. The surround attached to the lift up cover, and rested against the left and right rear uprights, and on top of the plexiglass switch protector when in the down position. This gave support to the cover, and then that screw through the top cover would give support to the pin rack , thus preventing any sagging of the pin rack.

Foul line bar.
I was missing mine, just made one out of 1/4 inch brass rod from Menards, fabricated two brackets, painted gold, done.

NICE, VERY NICE.

And I thought I had alot of score reels to clean ! Dying to know how the missing pin mystery got solved, where did you find one? Looks First Class all the way. Always gets the most play at family and friends get togethers.