After owning and selling many Gitane guitars (500, 250M, 300, 320), I got another 300 last week as I discovered the updated (huge) neck and liked it a lot. However, I found myself facing my old nemesis, the 'wetness'/sympathetic ringing on the guitar. As I was aware of this, I had no issue with it, as I had fought hard to fix it via the usual methods: leather in tailpiece, shoelace behind the bridge, etc. But on a clever state of mind, it just came to me that the problem is mechanical, hence the solution is to inmobilize the strings when not used.
Just added a capo on top the zero fret...problem is gone.
It is no invasive, and I can still play first position. Of course, open strings sound muted, but ...that works for me!
Anyway, I looked around the web and this forum for a similar tip, but haven't found anything so...at risk of discovering the wheel again, here is a short video I shot. I hope someone would find it useful https://youtu.be/2VbFIfkgMIs