A puzzle

There is one mechanical design flaw with Solar Ride.

The ball can and will get stuck in the playfield, up near the shooter exit.  There's a gate back to the shooter lane with a spring-loaded switch to award 500 points when the ball passes through.  However, sometimes the ball will get caught by the wire gate instead of rolling into the playfield.

I've dreamed up an electronic / electro-mechanical solution:

"If the switch is on for more than a few seconds, activate a solenoid that changes the spring tension, forcing the ball back into the playfield."

It's so simple!  Just one sentence!

However, after some cursory research, I have discovered that delay circuitry is far from simple.  Do I use a timer IC like the NE555 to introduce a delay?  What about an op-amp and a capacitor, can I get a few seconds out of that?

I want to make this component as simple as possible, but am so far unable to come up with anything that doesn't use a timer device.

UPDATE: There ended up being a much simpler fix for this problem.  The upper mounting hole for the wire gate is fairly large and there's a lot of play.  When the ball was getting stuck, I saw that the return spring for the wire gate was rubbing up on the edge of the through hole in the playfield - changing the return force and not letting the wire bail push the ball through.

Loosening the mounting screw to move the upper post away from the binding edge reduced the problem quite well, and now it hardly ever gets stuck.