In photo 3 the finger looks to be held back because the payout disc is slightly in the way. Is this the case?
In photo 2 the lined up three bells appear to be at the back of the machine not in the payout position at the front. Why is this?
In photo 1 the finger seems to have gone through two holes but not gone far enough to go through the third hole. If you push it by hand is it stopped solid or will it push all the way quite easily?
If the answer to question 3 is that it will move when pushed, then the finger springs are the first (but not the only) possible culprits combined with dirt and old grease spread along the payout train.
If the answer to question 1 is yes then the payout discs are slightly out of line and the easiest way to fix MIGHT be to slightly bend the finger (bending parts, slightly and with care, has always been an acceptable method right back to when they were made at the factory).
If the answer to question 2 is "I thought you just needed to line up a winner anywhere", you're wrong. They need to be in the payout position. I think you already know this, but I can't make sense of the photo as it is.