HP27 : decimal dot and question on keyboard

[albertofenini]

Hi everyone,
today we worked on one of our collection unit, an HP27.
It had some oxidation and we wanted to be sure to store it clean.
By doing so, we also tested some spare parts we had purchased many years ago,
these were LED display for the Woodstock serie.
To our surprise, and we wanted to share it, the decimal dot, is not a dot, but is a small triangle.
Anyone knows which kind of display is this ?

We also noticed some oxidation underneath the keyboard, we injected from the keys some
drops of Deoxit, and it worked in a way, but we are afraid the sooner or later, we will have some
bad surprises (look at the upper right corner and you will see the shadow of some oxidation).

Question is : being this completely sealed, how can we clean this type of keyboard without opening it ?
Thanks for help !!!