Send to Viberg. I found out the hard way that they are the only place that can keep the double row stitching. The stitching on my boondocker resole is awful and it was done by a highly reputable place.
I grind finer for Chemex than the chart indicates, more toward what they have for siphon. I base it on extraction time. If it takes less time than my target, I grind finer. If it is takes longer than my target, coarser.
This occurred to me this morning. Think of roasting coffee as a chef adding salt to food. There is a point where the salt enhances the flavors without tasting "salty." Anything less and the flavors are subdued, anything more and the taste of salt masks the flavors of the dish. There is the same sweet spot with roasting.