Problems with my T400 keyboard

Ok, so some updates (good ones or maybe not).
I noticed that while the underscore key was unusable, I couldn't also use the combination LeftShift + Asterisk key (the one that has both + and * for math applications). The RightShift worked but the LeftShift only would work with letters not with the specific key I mentioned.
I kept blowing air and trying to get the underscore key cleaned, and it eventually did. Now the combination of LeftShift plus Asterisk also works, but the underscore key still sometimes gets printing like crazy. And other moments it doesn't work again. I cannot figure out what it could be, seems like the keyboard is not recongizing the keys properly.

Any help? THANKs

Hello GNUser
I have got a refurbished laptop (X200). Maybe sooner my laptop is going to fail as yours, maybe no...
Tell me that's not a solution, but I connected a USB desktop keyboard and is working ok.
Only a suggestion.

Well, good news, I took out all the keys, gave it a good cleaning (vaccum cleaner, both inlet and outlet air) and it seems to be working OK now.
I know I could use a USB keyboard but right now with the whole virus thing and all it would be a real problem for me if I was left without a working unit as laptop. I am glad that it seems to be working.

My advice for myself and other... clean your machines more frequently :)

Well done GNUser, you gave me an advise and not the contrary.

I guess I spoke too soon... :(
The issue is still occurring, in a random manner. The minus/underscore key doesn't work, but suddenly the machine will think it is being pressed (which makes the computer stop what's doing due to the error).
I don't mind the key not working (would just remap it to another key) but I need to solve the issue.

Is it possible to disable it in software somehow, in a way the hardware doesn't get affected? I have a T400 librebooted, Trisquel 8.

Any help is welcome!

If you have some isopropyl alcohol (Higher concentration means less water) you could try and clean the membrane underneath the key caps. I advise you to still be gentle, maybe with an earcleaner.

Thanks, I will try later Beko, don't have alcohol available right now (due to the virus situation).

In the meantime I used xmodmap to assign another key (one I don't usually need) to be the minus and underscore key. The one that was giving me trouble I disabled with:

sudo xmodmap -e 'keycode 61 = '

I don't know however if this will work in the long run, since I believe this is a hardware issue. Still looking for a command that actually tells the hardware to disable the key in question (instead of just mapping an empty value to it).