I’ve never set up a Huret Allvit but from the photo, I was also thinking that the distance from the upper pulley to the bottom of the cog seems to be too much. I was fiddling with my semi-modern road bike last month thinking that my B tension screw didn’t have the upper pulley tracking my cassette tightly enough. Turned out that I had an incompatible chain (Taya) and when I went back to my SRAM chain it was fine again.

so... #1 I would suggest trying a different chain - you never know, a new one might do the trick.

but before you do the chain, I looked again @ your housing loop. It appears to be too short. If you use a piece of housing about 2.5” longer, the added length could just goose that cage forward to make the upper pulley track better with the “grindies”.

I’m curious if this will help....good luck!