IBM Model M - 1986 - Some Keys Non-Functioning?

[Viper50BMG]

Hi all!
I'm a new Model M owner (or at least, I'm trying to be), and I've got a 1986 Model M with a few issues. 





I got it years ago as part of a bunch of computer donations for my BSA Eagle project, and, when I was cleaning out some unused bits and bobs from said project, I came across it.  It was missing some keycaps, and was a bit dirty, but it cleaned right up and, with the addition of a USB cable to replace the AT cable (bought from here http://www.ebay.com/itm/271367683396?_trksid=p2059210.m2749.l2649&ssPageName=STRK%3AMEBIDX%3AIT), it seemed to be identified and function on a PC. 

Unfortunately, my excitement was short-lived, when I realized that several keys were decidedly non-functioning.

Here's the readout from Aqua's KeyTest:


So,
Space, N, B, ?, Keypad -, RightAlt, DownArrow, LeftArrow, and RightArrow don't seem to be functioning.

This keyboard has a reputation for being an incredibly solid piece of work, and I'd love to see it clack again.

Any thoughts?

Thanks in advance!

(As I'm not sure that those attached images are actually functional, here are dropbox links to them:)
https://www.dropbox.com/s/6pejpbm692mxv98/1986%20Model%20M.JPG?dl=0
https://www.dropbox.com/s/ga34pbob1ubgf2h/1986%20Model%20M%20Serial.JPG?dl=0
https://www.dropbox.com/s/tab8yyie3i7xzws/IBM%201984%20Model%20M%20Keyboard%20AquaTest%20Results.PNG?dl=0

[dorkvader]

looks like the last row is out. If you open it up you might be able to repair the membrane.

[mougrim]

Did you try to remove keys and re-seat them?

[Viper50BMG]

Mougrin: Yes, I took everything off, cleaned it, dried it, and reseated it.  No go.

Dorkvader: Any suggestions on tutorials for tearing it down, and what I should look for once inside? 

[mougrim]

Mougrin: Yes, I took everything off, cleaned it, dried it, and reseated it.  No go.

Dorkvader: Any suggestions on tutorials for tearing it down, and what I should look for once inside?

There are quite a few video-guides on youtube. About what to look... you'll probably need to do bolt-mod anyway.

[E TwentyNine]

There are quite a few video-guides on youtube. About what to look... you'll probably need to do bolt-mod anyway.

A bolt-mod is not inevitable in this case.  As Dorkvader notes, it's one common row out, which means that trace is having an issue up near the connector.

Reseating the small connector is the first step, cleaning it gently is next.

[dorkvader]

There are quite a few video-guides on youtube. About what to look... you'll probably need to do bolt-mod anyway.

A bolt-mod is not inevitable in this case.  As Dorkvader notes, it's one common row out, which means that trace is having an issue up near the connector.

Reseating the small connector is the first step, cleaning it gently is next.

^this.

It means there is a problem with connecting the trace somewhere along it (usually near the connector). Reseating it can fix this. Other people have had success by other things like cutting off the end of the membrane and plugging it in again, or replacing parts with a bolt mod, but it's not knows what steps are necessary to repair this.

issue is most probably connector issues with the membranes near the connector (pretty common) in which case reseating the cable will likely fix. It could also be a break in the trace for that row on the membrane, in which case you'll need to repair the membrane with conductive fluid or replace it with a working one. IT could also be other things as well but the first  step is to open it up and reseat the membrane connector.

To open it up, get a 5/32 thinwall nut driver (I use a 5.5mm and it works great) take out the 4 screws in the back. The case then comes apart.

It is possible to take them out with a very fine pair of needlenose pliers but I do not recommend it as you can damage the pliers and the case.

[Viper50BMG]

Thanks, all.  I'll see if I can find a small enough driver to thread the needle.  I'll try reseating the ribbon first.  Would a broken trace be visually identifiable?  Or would I have to break out a multimeter to find out?  Any recommendations for conductive fluid?

Thanks again?

[Puddsy]

Thanks, all.  I'll see if I can find a small enough driver to thread the needle.  I'll try reseating the ribbon first.  Would a broken trace be visually identifiable?  Or would I have to break out a multimeter to find out?  Any recommendations for conductive fluid?

Thanks again?

Depends on how broken the trace is.

I'd get the multimeter out anyway, but I just like to use my multimeter.