Shameless plug here for the Pinball Ninja-
In case you don't know who he is, are new to the hobby, or just don't have a Ninja account yet!

from his latest Ninja blog entry:

"Have this nice 1973 Gottlieb Jumpin Jack EM pinball. I’ve had it a long time, and it’s gotten a fair bit of use. Used to operate it too for a couple years at a local video store. But anywho, lately it has started to have problems resetting. Press the start button on the coin door, and the “cla-chunk” noise for a long time until it “hit” and the game would start. Also between balls it could do the same thing. So I knew something was up."

To read the rest, and watch a 9 minute video of the repair-
Log into your account (or get one!) Lots of good info for those new to troubleshooting EMs(who seem to be on the rise lately)

Here ya go:
http://pinrepair.com/donate/
($20 will get you lifetime access)