some also make their own by 3d-printing them hehe
both sounded like key chattering. you can try blow compressed air into the affected switches (stuff like lens blower works also), and see if it helps: take off the cap, press the slider down, and then blow air into the switch. you should spam the switch for a while also.

usually air blowing trick should do the job well. if air blowing is not working, you can still desolder and tear the affected switch down, then clean it up, then put it back. or, you can just replace it with a good one.

if it's still not fixed, it might be something else at fault.