Looks like a driver is out to that segment. The displays are very likely mutiplexed. A schematic would help make educated suggestions.

No harder than an early solid state display.

No, probably just a bad chip.

I think that might be a model H or S skeeball, although I'm not to familiar with the differences of all the models. There's scanned documentation and schematics floating around for most of them.

Here's what the display board looks like. They're actually just bulbs, rather than display segments.

pasted_image (resized).png

There is a brand new display assembly available for $175 which is very nice (made by the same person who made the WPC kahr daughter board):
https://kahr.us/

Example of a Model S MPU:
pasted_image (resized).png

Have you attempted swapping bulbs. The bulbs are often a problem but the legs on the sockets break frequently.

It's hard to tell if it's the LED version or the incandescent it could just be bad bulbs or bulbs/sockets.

So Skee-ball lanes were designed so the parts from a model H or S could be interchanged, sometime you will see Model H lanes with S displays ect....

Model H displays are the easiest to identify. There are separate PCB's for the large score numbers and the smaller score count number. The actual "segments" are light bulbs with a plastic lenses over it in the shape of a digital number. Each number has two chips controlling it. I've seen instances where one bad chip causes all the numbers to act funny. The most common issue I've seen with these are the bulb sockets being brittle and broken. The bulbs for the numbers are 73's and 74's.... you need to use the correct ones in the right spots.... I can't remember off hand but I think the score numbers are 74's and the smaller ball count numbers are the 73's.

s-l400 (resized).jpg

Model S displays came in two flavors, they are all one board for both the score numbers and ball count numbers, but some were built using light bulbs (again 73's and 74's) as the digits. These also used two separate chips for each digit (Basically the same circuits design just everything is one one board instead of two, so the same issues apply as above).

045ece9090e58dd2884cf3befe4d0632ce6fa497 (resized).png

The second version of a Model S display uses actual large LED seven segment displays. These used one chip to control all the numbers (this chip has been out of production for 20 years and is getting difficult to find, I don't remember the number off hand).

SKEE-BALL Arcade Machine Game PCB Printed Circuit SBD4 MODEL S DISPLAY Board for sale_1 (resized).jpg

Also.... if anyone is interested.... Model "S" Stands for Electronics built by Skee-ball.
Model H stands for electronics built by Deltronic Labs.
There is also a Model V that looks identical to the H and S on the outside, but the electronics inside are pretty different. They are pretty rare and I've only ever seen one. V stands for electronics built by Vangaurd.

~Jeff

I have this replacement in mine, it is worth every penny. Otherwise you are signing up for a lifetime of rickety and scorched bulb socket repairs that never seem to end.