Gill
no need to start allover.Clean it realy good with acetone, use fine 3-M pad as MP said and start rusting.

BrentD
One of my customers allways send me parts for rust
bluing that he polished them to the piont you can see youself
in it.In the past i try to blue those like he prep them,I had
more problem than i wanted. i was ready not to do any of his
jobs.He would not lisened to me.
Now when i get parts from him i just use my magic Scotch pad
and blue rhe parts exactly the way he want it.
Casey