Niels,
First of all, phew, what a post! Truely magnificent.
I've had a thought about the Hotchkiss in the dump with the "4"/"7" number. I think it might actually be "22x". See the (hopefully) attached image...the "22x" seen at an angle could fit. Also, the little protrusion on the turret side could be responsible for breaking the "clean" lines of the digits.
Best regards
Aris Kosionidis
