The plunger (ball shooter) is sometimes overlooked when a machine is
repaired. Here's how to tune up your plunger.
1. Remove rubber tip. If you're going to replace the rubber tip you
can easily remove it using pliers or wire cutters.
2. Remove end retaining clip. Williams uses a disposable C-clip that you
should replace with an E-clip, but you can re-use it if you are careful and
do not bend it out of shape too much.
3. Remove any washers and the long plunger spring.
4. Remove the plunger rod.
5. Remove the outside barrel spring and any washers.
6. Clean the plunger rod, washers, and springs. You can use Wildcat #125
or alcohol, or almost anything else that removes the dirt and sludge.
7. On Williams plungers you may need to replace the plunger sleeve. This
is a nylon sleeve that looks like a long narrow coil sleeve. Note that the
flange side of the sleeve belongs on the inside of the machine with a washer
protecting it from the inside spring. Be sure to clean the inside of the
plunger housing, or old plunger sleeve. I use Q-tips and a solvent like
Wildcat #125 or alcohol, or even Novus #2 (not a solvent). Dirt in this
area is usually what makes a sticky sluggish plunger.
8. Place the outside barrel spring on the plunger rod (replace if needed).
I prefer to use Gottlieb-style outside barrel springs because they have a
chrome finish and thus look better.
9. Insert the rod into the housing. Washers usually don't belong on the
outside of the plunger housing. Washers on the outside will pull the
plunger out away from the ball, and in some cases will prevent the ball from
being struck solidly.
10. You may place washers on both ends of the inside spring, but it is not
required except on Williams machines due to the plunger sleeve.
11. If the inside spring is too weak you may replace it with a newer
spring, a stronger spring, or you may just stretch out the old spring a
little to give it more tension. Note that some machines need strong
springs, and other need weak springs--Twilight Zone must have a very weak
spring, and High Speed must have a very strong spring.
12. Replace the end retaining clip and the plunger tip.
13. Check the plunger alignment by lowering the playfield into position see
that the tip is in the center of the ball track. If it is off-center you
can loosen the plunger housing and reposition the plunger. If you find that
you cannot get it close enough you may find that your plunger housing is
upside down! If your alignment is off the ball will not be struck on-center
and it will move weakly and chatter from side-to-side going up the plunger