check the gear on the starter, they are made of plastic/polymer and when
wear out / fail a grinding noise will be present. if it is a older style
starter all you need to do is knock out a roll pin to change the gear but a
newer style has a c style clip ring which is a pain to get off unless you
have the proper tools. for the newer starter I would take it into a shop to
have the gear changed if you have any doubts about doing it yourself.