: that lies to one side of the centreline and is about ¼ of an inch wide,
: how on earth am I going to achieve a satisfactory. finish here??? I did
: write to Nick and it didn’t seem to him that it was a great problem but
: the more I look at it the more it worries me. What to do??

If Nick said it was no great problem, you might be falling victim to your own perfectionistic bent. I do it all the time with my oil paintings... groaning about something nobody has the slightest clue about.

Pete