I have a 2017 and my "b" key sometimes repeats and sometimes it doesn't enter at all. Some other keys have had some minor issues too. I tried using compressed air this morning and it didn't fix the issue. I'm on High Sierra, so I will be downgrading to Sierra, but I highly doubt it's a software issue. It seems if I press the key extra hard or press directly in the center, it works (but still repeats). If I press the key on the left side, 25% of the time they key will not press. I'm going to call Apple this afternoon after work but I am wondering if anyone else has advice.