Originally Posted by SparkieSRT6

There is a pen available that has many strands of glass fibre that retract in and out of the pen tip as required. Very abrasive and it will remove the rust and get you down to the bare metal ready for touch up. I have used it will great success. Be careful not to work outside the area as it will quickly remove paint too. I bought mine many years ago at Canadian Tire. Similar to this one :K-Tool International (KTI70550) Sanding Pen: Sanding Discs: Amazon.com: Industrial & Scientific