Restore a Pioneer keyboard (27s)

[franz.b]

I closed the keyboard. The touch is great and it seems that all the keys are working. I forgot to photograph the tracks before closing, I reinforced some with a conductive marker because they were ruined by the water that had entered years ago. You can see the first two tracks on the right retouched and another on the left, but for those on the right I had to go back a few centimeters with the conductive paint.
I discovered that the plastic films that make up the keyboard are 4 and not 3 as is often described on the web.
It was very difficult to handle the microscopic screws, I made a pre-hole with a hot needle before inserting them.
Unfortunately 2 keys do not work: down arrow and shift.
From the layout of the keys they have a common track but this is in common with other keys that work, so, if I think well, the problem must be in the contact under the buttons ... I'll have to open everything again! ? but luckily I didn't use the plastic welding or glue method!