Tactx Keyboard. Where to source replacement parts?

Hi

I own a Tactx keyboard which is out of warranty.  Recently, the space bar, 's' and '/' keys stopped working.  I have tried a different keyboard on the pc and all these keys work.  I have also plugged the Tactx keyboard into another pc, and the same problem persists.  I assume that it is therefore a hardware problem.

Due to being out of warranty, I decided to remove the back of the keyboard to see if there was anything obviously wrong, such as making sure all the ribbons were held in tightly.  By doing several tests, I have determined that the top layer of the keyboard circuit sheet (not sure what this is called) is faulty for those 3 keys.

Do you know where I might be able to get one of these circuit board plastic sheets from?

I am based in the UK.

Thanks

Piers