Tandem Cycling - Flight Deck malfunction

Anyone shed some light on what might be wrong here?

My captains 'puter more often than not will indicate that the cassette is in the biggest gear (indicater far left) when it really is not. This seems to be after hitting a nice bump...sometimes just because it wants to. Is this a problem in the shift sensor? Seems I can sometimes get it to stop by moving the head unit around on the base, but that may be just shear coinkydink.

Since you believe you may be able to make it work by moving the head unit, I would suggest that you take the head unit off of the base and clean the contacts with an eraser or some very very fine paper (600 grit or higher). Don't use course paper or you'll remove metal - you just want to remove any dirt or oxidation.

Another possibility is that the contacts where the wire connects inside the lever are not making good contact. If you peel the hood back you will see on the inner surface of the side of the lever two small screws that hold a small plastic cover with the button over the connection. If you take it off, you will see the small connector on a leaf-plate that is supposed to be bent out enough to make a firm contact with the button. Anyway, you can pull the leaf-plate contact out and bend it out a little bit. My manual shows and says to do this if the gear display is not correct. I am giving a link to the current document on the Shimano site and I notice that instead of saying to do this, it shows attaching a "sticker" to build out the area a little higher but I know nothing about the sticker and I went back to my manual to confirm that it doesn't talk about that. Anyway, I have fixed gear display problems by bending the leaf-plate contact.

Here's the link: Have fun and good luck.
http://techdocs.shimano.com/media/techdocs/content/cycle/SI/CycleComputer/7AP1D_En_v1_m56577569830604501.pdf

Bloomington, IN 47401

Yes the contacts are really sensitive. The installation instructions that come with the unit do say you can bend the pin pad to help make better contact.

Pull the rubber boot back as far a you can to gain access to the plastic plate that holds the pin pad in place. Remove the two screws to adjust the pin pad.

Based on the above advice, I pulled the boot/cover and removed the plate. I managed to determine that the problem is somewhere in this component. I could make it worse and better by playing with the contacts. Still it does not seem to work perfectly like it used to. I'm afraid I'll have to replace the wiring harness. Looks like it's all sold as one set.

My next question has to do with the sensor that is in the shifter itself. Where does that piece come from? Doesn't look like it's sold as part of the wiring harness set:

...the sensor that is in the shifter itself. Where does that piece come from? Doesn't look like it's sold as part of the wiring harness set:

The part in the shifter comes pre-stalled in all FliteDeck compatible shifters. I've read in various places that one cannot get spare parts for the insides of Shimano levers. I wouldn't mind getting my hands on a discarded lever so I could see if I could get it apart.

Bloomington, IN