Hello experts

We have 2 Hermle C600 milling machines with Heidenhain controller.
Now the keyboards on both machines are defect.
Either the keys are blocked or things get entered several times.

A new keyboard from Hermle costs 1000 ,-Euro in exchange. There are no single spare parts for the keyboard available. (e.g. like the rubber plate or the circuit board) Heidenhain says similar things.
I think that is very expensive and it’s sad that there are no spare parts for it at all.
On our old CNC with TNC 155 the keyboard is more than 20 years old but on the new controllers we had to exchange it at least once in the past ten years.

We had no improvement cleaning the keyboards either.
Is that normal- what are your experiences?

Regards Gusto