Stripped screws that hold keybed on Grandmother.

Hi, when fixing the spring reverb on my new Grandmother I accidently unscrewed the keybed before getting her open. When screwing it back in I noticed one of the screws wouldn't tighten and plastic shavings would fall out. I noticed the keys didn't feel great, so I opened her up again and tried readjusting the position of the keybed. Upon screwing it back in, I noticed more screw holes were stripped.

Now the keys feel bad to play and some keys produce annoying little clicks. What's the common approach to fixing stripped screw holes on synths?

Thanks.

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