On your machine, United stepped it up a couple notches with its scoring.
In the 7th, it is suppose to give 210 (as the backglass indicates) for a strike.
On most shuffles, the extra shots is or the 10th frame, but your machine
states Extra Shots Frames, so I can't say what Frames those would be.
Perhaps there's a setting in the head (maybe the coffin) where frames can
be set for extra shots after making a strike(s)..
I'm not certain why it scored 50 points in the 1st frame for a strike.
I could be that the 10 - 90 Relay is a bit flimsy and vibrating while energizing
making the contacts trigger additional times.
You can stiffin' it up by twisting the longer blades so that it has a bit more
resistance to energize, but of course is yet able to make its travel when energized..