Keyboard: some keys stopped working

Some keys on my Librem laptop keyboard stopped working (gradually). Currently the right arrow key, and the numpad keys 4, 5 and 6 don’t work most of the time. Is there a possibility of a keyboard replacement? Or something else that could be done to make those keys work again?

Try cleaning the dust with a compressed air.

Thank you for your response. I got some compressed air and tried to clean the keyboard. Unfortunately, the same keys are still not working

They do not work at all? Is the numpad lock off?

Unfortunately they do not work at all since a few weeks. With numpad lock on, the keys 8,4,5 and 6 of the numpad do not work, with numpad lock off the same keys do not work as arrow keys. And the arrow right of the arrow block does not work.