there is probably dirt in the switches, if you can do it, open them up and clean them out. this can be risky if you are not careful and some switches cant be opened and then put together right so be carefull of that too. Khali swiches are low quality in the first place and i generaly wont recomend anyone buying them, there are other swiches that are better in the same price boards often, like Gateron switches. if you have access to an air compressor ot canned air you can try using that to blow on the switches