Been doing some research on why this is happening.

SYMPTOM: Left flipper intermittently will either drop (while crading, for instance) and re-hold, or flip-drop-and quickly reflip.

DIAGNOSIS: Been led to believe this has something to do with the hold coil.

THOUGHTS: The intermittent nature of it (meaning it doesn't happen every time you hit the left flipper button) seems to suggest some mechanical issue, like dirty contacts or something or even an unsoldered lug.

The issue is I'm still very much a newb when it comes to repairing games, though I have done a few (successful) repairs (replacing VUK switches; re-soldering some things; replaced a DMD).

Can anyone more experienced suggest an approach to troubleshooting this? I can put the game in diagnostic mode, but the coil seems to fire... and all that.

1) What should I try in the diagnostic mode and what should I look for?
2) Should I skip the diagnostic mode and either clean or check something?

It seems to me (bad eyes--I'm farsighted) that the soldered connections are OK, inspecting them by hand.

Anyone see any obvious things to check? (Photo evidence). (Can provide further photos if needed)

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Thank you!
Chad.

Thanks guys... I'll take a look at these things after work. I'll clean the contacts and check that PDF, as well as reflow solder. The mosfet thing may be a good lead. I do have a multimeter and would rather test with that then pull out the coil. I'm guessing there would be full power to the coil if I keep the coin door shut with the playfield up. Or should I just be testing for continuity?

Will also check the board. Should be one of those things, hopefully!

Well, after running through the cleaning of the EOS switches and playing about 25 balls for well over an hour, there's been no issue. Thank you Razon and Wizewum (and Vid). The crisp dollar bill/EOS cleaning thing seems to have done the trick.