It seem to be hard to find the correct one..
Here is a site with lots og inside pictures. Maybe by contact (bottom of the page) could be for any help?
http://www.deepsonic.ch/deep/htm/gem_wx2_plus.php

The owner / usermanual for WX2/WX400 is downloadable from the site, but it probably won't help you much..
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Cheers 🥂
GJ
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"Success is not counted by how high you have climbed
but by how many you brought with you." (Wil Rose)