The YHM can should have come with a set of spanner wrenches, and both the can and the phantom mount have indexes for these wrenches. You can buy a steel spanner wrench from YHM. The brass/bronze wrenches they ship are soft and will eventually bend break (ask me how I know). I usually index the wrenches on the can/mount with everything lying on the floor, such that the floor is applying opening pressure to one wrench. Then I tap on the other wrench with a rubber mallet until it all pops free. Works every time.
The nomad also uses a spanner wrench. Same trick… I’ll try to create an image if you’re not getting what I’m writing…
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This is the wrong wrench for the mount (I sheared the lug on my other brass spanner), but taps/hits downward on the silver colored wrench will break the mount free…