Locate the relay that scores 50K points. It's probably mounted on the bottom board, and is likely to be a standard size relay (what Gottlieb called a "magnet type" relay). If this relay is sticking, either electrically or mechanically, you'll get the problem you are seeing.
If it's a magnet type relay, and it's sticking electrically, you'll probably need to adjust the lock-in switch of the relay, and you may also need to adjust the motor switch that releases the relay at the end of the scoring cycle. The motor switch is almost always located at position 2B of the score motor, but check your schematic to confirm this.
If it's a magnet type relay, and it's sticking mechanically, you can remove the armature plate from the relay, and clean the inside face of the armature plate, and also the center pole of the relay coil. You may also have long switch blades on the relay that are not providing enough back-pressure on the armature plate for the armature to reliably release at the end of the scoring cycle, so you may need to adjust these long blades to push on the armature more, in the direction away from the relay coil.
- TimMe