Paul – When You talk about using the coping saw, I think You think about ONLY using the coping saw to remove waste. Not an issue for us regular people 😉
Gary – I agree with your suggestion to chop from both sides and I do so…in my description of the method I used a “mental shortcut” 🙂
Jeff – As I look at your diagrams, I get the feeling we were talking about to different problems. In the issue You are describing the solution may be a chisel with the side thickness reduced. As Gary mentioned…grind or file a chisel or get and old Marples or new LN, Blue Spruce or Veritas (by the reviews the are so thin one has to sand them a bit to not get hurt :)). Anyway, I haven’t found a problem with this part of dovetailing.
What I had on my mind was when cleaning the space between the pins. How is the chopping done, not to mar the pin walls? On my diagram the area giving me the issue is colored in light grey. What I do now is chop down from both sides the width of the narrower part of the tale (yellow) and then pare the remaining triangle with the chisel (orange). Is that what you do?