My touch not working

I bought this Kobo a while ago. It had a problem with the touch screen, which didn't work properly or in some cases didn't. Disassembling the touch screen works with an IR frame, but adjusting it, cleaning it, and checking if the photodiodes are working. In this case, the transmitters are working.

How do I check if the receiver photodiodes are working?

Does anyone know if the photodiodes or the touch screen can be calibrated?

Does anyone know where I could buy those photodiodes?