You have to adjust one of the stop brackets (L-shaped) that are on the baseplate, IIRC.

Right, just the reel.

on the back of the reel (metal plate) there is a set screw in a slot that decreases the "sloppyness" of the reel rotation....

Yea, can be very tricky. Like adjusting the stops on a roto target...

roto target is a walk in the park compared to those rat traps
I still haven't mastered lining up the numbers

I came across this 4 year old thread on a google search yesterday when I was seeking to resolve score reel number alignment on my recently restored GTB 1965 Skyline. The GTB rat trap score reel is certainly an interesting design piece and I must say not the easiest beast to master.

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I contrast this to recently servicing 24 score reels on my United similar vintage ball bowler. They were well designed and in comparison a breeze to service.

Although I must commend a tip, and a fuller rat trap explanation, on pin wiki which suggested to ease access to the mechanism de-solder the wire from the circuit board which enables the board to be lifted and moved aside giving good access.

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The screw referred to earlier by pinhead52 is the allen head screw shown below which enables the ratchet stop to be adjusted.

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After several hours cleaning, servicing and tinkering with the mechanism I concur with earlier posts that consistent alignment of all numbers on a score reel is a difficult task. In some ways I found trying to resolve this alignment issue on a rat trap similar to trying to get a cantankerous AX relay to play ball. On the rat trap I found it very difficult to perfect the stop adjustment to remove ratchet sloppiness while not adversely affecting switch settings and general score reel ratchet operation. So I have reluctantly accepted that non perfect alignment of score reel numbers is part of the character of these mechanisms.

Some time later I may try a couple of spare rat trap mechanisms I have but for now I will live with the character.

Probably one of the major reasons they radically changed the design.
I'm a Gottlieb guy, but IMHO, Bally had the best score reel design in all aspects.

And Williams. Their designs are very similar. Williams and Bally are Japanese cars to Gottlieb's German cars here. Overly complicated piece of engineering, fiddly to get dialed in and keep dialed in.

Williams and Bally, once they are dialed in, are rock solid. I have a Bally Surfers that was basically stored for near 20 years. I fired it up and the reels worked perfectly. Try doing that with a decagon.