That's a valuable suggestion, honing with a steeper angle till I strike sound steel.
I was too optimistic last night. Honed some more today, to deal with the neglected tip, and all I found was more crumbles... But there is noticeable improvement, compared the the initial condition.

One of my problems with this job is tool related. My DMT-C and F both have lapped a vast amount of Coticules, and although not completely worn out, the diamonds have been tamed seriously.

More work tonight. I'm going to take your advice on the tape.

Speaking about tape: you're right. Not only because it introduces unevenness at the spine (The spine of the W&B is very uneven to start with), but also because multiple layers introduce a clear cushion effect, preventing any crisp keenness if you apply the least pressure. The solution is to use aluminum tape underneath one layer of electrical tape. (Oddly enough the electrical tape seems more wear resistant than the aluminum).

Thanks for the good observations,
Bart.