In my lifetime of fixing stuff
When it goes bang bang in a nasty sounding way it generaly sends metal bits through out the motor
SO if you open it up a bit and see anything that got eaten you will need to take it apart and REALLY clean things up it its going to live
IMHP you need to ID what you have first and look into if you can get parts and a manual before you waste much time becasue you would be supprised what you can FUBAR buy taking something apart without a manual