This game has a "beater bonus". The bonus reset is constantly
pulsing during game resets and when the ball is served. So
consequently, the coil stop gets pounded to an unusable condition.
Once the bonus unit was repaired with new components, I added
a switch to the stack so as to make the reset coil stop firing
once the bonus reached zero position. In all, the game played
quieter and cleaner by this mod.

I made the reset coil reset the bonus; as in regular gameplay/mode. However,
The reset coil( by the game design ) gets five pulses from the timing motor.
Thus, even if the bonus is completely reset for a new game, the bonus
reset coil is still pulsing.
Wich, in turn, wears out the plunger and coil stop.
Thus, by adding a limiting switch to the reset coil, it stops it from activating
once the bonus unit has completely reset.
Finally, it saves the coil plunger and coil stop assemblies from wearing out.

Remember, the bonus can only be collected at the right side kick up assembly;
not the out hole.

In all, it is like the limiting switch on the credit assembly.

I just got done with a Gotlieb Big Brave, and it too has
a "beater bonus" set up from the factory. However, it
was not mine and so the coil stops were changed and
that was it.

Did you relaxed the rubber ring before you installed it?
I always relax the rubber rings when they are new.
You might have to make your own new plastic or hopefully find an old used one somewhere.

EM-fan
Tip: you can add shrink tubing to the stop-end bracket if you do not want it to have metal on metal contact.