Already done:) Works like I experienced on your DarNico.
Perfect and simple. Once it is set at the right tension you do not need to touch or turn the black nuts again.
(Maybe once in a while a little added tension)
Just like Henry Amel intended it I would think.
No difficult systems. I just needed to sharpen the edges of the retaining groove as they flattened a bit over the years.
A little silicon spray and the varnish doesn't scratch:)
Thanks for the reminder