+1 on starter motor.
mines doin it too.
Dam 33 starters.
Mine did it a while ago, about 2 yrs to be precise.
Took it out, greased it up, was dry as a bone.
hooked it up to 12v battery, let it spin a couple of times till the noise went. Sweet as.
But its startin to do it again, might just replace it this time round.
RJ