Have you taken a look at the fuse clips on the flipper board in the cabinet? How does it function in test? Anything inhibiting the switch for the flipper button on the inside of the cabinet from activating consistently?

There is a (hard to find) technical service bulletin about this. The EOS switches are wrong / weak and need to be changed with upgraded ones. Do this, jump your EOS switches with a jumper wire and I bet they will work 100% of the time. We had to do the same thing for my neighbors before swapping eos with upgraded model.

Jurassic Park flippers... even seasoned repair technicians don't find these easy.

Reliable operation of these flippers depends REALLY STRONGLY on the End of Stroke switch. Those contacts have to be really tight, I mean insanely tight, tight enough that they really really really make good connection.

That's why the above advice about using some alligator clips and jumpering them closed is the quick and dirty get it working option.

Brand new End of Stroke switches may need further adjustment, so even if you think you've got the new End of Stroke correct, try making sure that those contacts are really tight, and properly adjusted.

It's also common to need to clean the End of Stroke contacts (and the flipper button contacts) with alcohol to make sure that they are making good connection.

However, There are two other absolutely critical parts. The rubber pad that the crank arm rests on when the flipper is at rest (not activated) was originally fairly soft. If it is worn through to the metal a harder rubber replacement is available, but the ones I bought recently didn't fit easily onto the flipper base plate. It took some work getting the part to allow the flipper to return to the proper resting position.

So, the rubber is important.

The next piece that is really no fun at all is the red cap that activates the End of Stroke Switch. This needs to be replaced if it is worn or loose. Reliable operation of the End of Stroke switch depends upon it!

Finally, the fuse holders on the TYFFASI flipper board are... poor. A fuse that isn't making perfect really snug connection can starve your flipper power, causing intermittent operation.

The flipper board may also need to be updated, check out the pinwiki for details.

This is the wiki section on Data East Flipper problems:

https://www.pinwiki.com/wiki/index.php/Data_East/Sega#Flipper_Issues

Do what the poster above says about jumpering the End of Stroke switch contacts together, and if that makes everything work with great flipper power, you KNOW that the work you'll need to do is all about the End of Stroke switch.

Let us know what you find!

The idea for the TYFFASI board was that you would have a single coil, instead of two different windings of different sized wire on one core.

The board will for a certain number of milliseconds apply full power, then switch to a much lower holding voltage automatically.

The End of Stroke switch restores full power when you are holding the flipper bat in the up position and a fast moving ball knocks it downward.

So when you bypass the EOS switch, you'll lose that function, where it will keep the flipper bat upward when the flipper button is pushed, even when a ball knocks it down.

You wouldn't want to leave it like that, the flippers are how you control the game, and they need to be right!

But it restores flipper operation, and definitely confirms that the troublesome End of Stroke or hold circuits on the board are your problem.

Did you try jumping it or just hold it closed using the contact points? If the ladder, jump from under pf.

Yup!