hi,new member,got myself a 2012 stx550 spanish a couple months ago,drove it a couple hundred klms.started to here a whine in the diff,checked the oil. there was none.took the bung out and got about a teaspoon of metal filings.cleaned it out and filled it with the proper oil,but it's still got a bit of whine. so,my question. is it better to get a complete diff. or get this one fixed