The target that it is scoring is kinda weird, only the *next* to last one in the stepper count, but not the last one.

The reset pawl seems be working since it can be moved by hand after you hit the outhole switch, and it is moving pretty good when it steps so doesn't appear to be too gummed up though it may be somewhat. There is a torsion spring around the shaft that returns the stepper to zero, see if it has come loose from the metal post it is attached to, or has snapped. If it looks okay, the stepping pawl might be just enough to work thru the gumminess but not the return spring, so put a drop of machine oil as indicated and move it back and forth a few times and see if it frees it up. When you turn it by hand like the video it shouldn't feel stiff, When it is stepping it looks sluggish in the video too like the shaft is gummed up.

184200959_854028598520848_2090053086867663599_n (resized).jpg

Correct, as it is stepping and scoring the bonis it is going away from zero position, then on the next ball or player it is supposed to be released and spin all the way back to zero position in a single motion.

Yay!
This was the first game I ever bought and fixed up about 40 years ago (Solar City, a 2 player iteration of Target Alpha). I was able to get it working right but believe me I did just about everything incorrectly that you could possibly do in the learning process. I feel sorry for whoever it was I sold it to because I even put lithium grease in the score reel solenoids which likely dried up into a dirt-laced putty.