Sam keyboard rubber mat

Hi,

I just opened, cleaned, lubricated and re-assembled the keyboard on my Sam. The thing is that the rubber mat between the keys and membrane is wider then the other parts. When I fix it to the place regarding holes and close the keyboard, everything work fine except keys J (hardly working at all) and F (working bad). Due the sound of the keys I believe it is because the rubber mat is misplaced on these two keys. Is there any hint how to assemble the keyboard correctly?

I tested the membrane to be sure it is working and those two keys work the same as all others, so it shouldn't be a membrane problem.

Any tips are appreciated!