"mm" wrote in message

I have a fin comb, but have made almost no progress straightening the
fins.

Is there a special technique I should use?

It is a two step process. You have to get then straightened a bit and
nothing to snag the comb by using duckbill pliers, Then you can use the
comb to align them. If you have one of those cheap plastic combs it takes
some time. Many years ago when I worked for a company that built
eating/cooling coils, they used a metal comb that was fairly deep.