My uncle used to recommend buying specific cleaners for cleaning amps and few other electronic devices, but my father and I were too lazy to buy those. We only cleaned the outside and we did it the old, simple way: not-so-wet cloth. We were not confident cleaning the insides although we had seen video tutorials on internet. Dad prefers to bring it to my uncle if it breaks. As far as I know nothing serious happened; we had one for years before we replaced it with a new one once it broke.