The lower left flipper is fluttering on my Medusa.

I have “cleaned” the contact points of the blade switches (by pushing them gently together and then pulling a thick paper through them) both at the button and at the coil.

I have checked the coil wires and cannot see that any of them are broken (as far as I can tell). See image below (there is a thin piece of tape holding them in place which makes it hard to see). I guess that the purpose of the tape is to protect the wires.

During the fluttering (flipper active) the contact point A (see image below) has a connection and B is disconnected. An interesting observation is that there are “flashes” flying between the contact points at B during the fluttering (creating a sparkling sound).

Any suggestions?

Could it be any of the diods? (What type are they?)

Is there a way to measure the coil and/or diods without desoldering anything?

Any other tests?

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3 ohms on the high power side (the same when the flipper wasn't held up)
and
6 ohms on the low power side (zero ohms when the flipper wasn't held up)

I also measured the resistance on the healthy side and the results were exactly the same.

The fluttering and "sparkling" take place when the flipper is up.

When I closely study the contact points of the blade switches, they look a bit weird, like someone might have used a file or something. See images below.

Another thought: could the problem have something to do with the coil stop?

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I measured the resistance across closed switches and it was 0.0 ohms. Despite this, I tried the sandpaper cleaning and it did the trick!

Maybe I should change all the switches anyway because they really don't look well (that goes for both the coil switches and the button switches). After playing a while, I get the impression that every now and then, the flippers are weak and maybe that has something to do with bad switch contacts.

Thanks everybody for the advice!

Having problems finding the correct switches (aren't there any parts catalogues for Medusa?).

Are the correct flipper button switches ASW-A10-41?

Which are the correct flipper coil (double) switches?

The Planetary Pinball link shows a catalogue which ends with page 47 (and the swithes are on pages 85-87).

Thanks, zacaj and Atari-Daze!