Assistance required

Dear Ladies or Gentlemen,

I have a question. I have a LUKS1 encrypted disk. On this disk essential
memories (familiy pictures, etc) are stored. But: I forgot the passphrase.

As far as I understand the passphrase only encrypts the master key on the
disk. If I'd able to add another keyslot with a known password I should be
able to access the data right?

But unfornutaley I need to know the previous passphrase to add a new one.
Is there *any* possibility to access the data?

I attached the header (first 2 MB offset 512 bytes dumped using dd).

Some Background information:

Acutally it's to 2disks that are part of a LVM Raid1 which were put in a WD
MyCloud EX2 Ultra Enclosure. After a power outage the enclosure does not
show the volume and thus I cannot export the passphrase for the volume.

After having the disks put into a Fedora Linux I can see the disks and
volumes and that the data is encrypted. Unfortunately I cannot decrypt them
using crypsetup due to the missing passphrase as described above.

I'd be very happy if it would be possible to access the data, because the
data is precious to me.