This is a common issue with Stern’s Jurassic Park pinball machine. The shooter lane throws the ball into a vertical up-ramp delivering it to the right flipper, but in some cases it doesn’t reliably do so and it messes up the skill shots. Here’s a fix that is based on what appears to be a manufacturing defect with the playfields.
I’ve been very excited about one of my latest acquisitions. A much-coveted Bally 4 Million BC pinball machine that I drove almost 1200 miles to acquire. The game is in great condition but was having a very unusual problem whereby it would kick out extra balls into play constantly. After going after the most obvious places and cleaning relays, then looking at the schematics and expanding my search, then finally going through every relay in the machine and cleaning contacts, the problem still persisted.
Here’s a description of the issue:
Then finally, it dawned on me. How obvious the solution was! But a very rare thing to see in an EM: a glitch that was the result of the logic design of the game and me being careless when I went to wax the playfield!