Usually I'm the first to say DMT but truthfully diamonds really don't work that well on SR101. They are effective don't get me wrong on that there just not any better than sandpaper simply because the steel is not wear resistant enough to benefit from what the diamonds offer.

My suggestion would be a piece of 220 and 1k wet/dry glued to a cut down paint stick. This would give you the option of light touch up or damage repair.