Huret spring tension

[CRASH]

Mechanics, I’m wrestling with a Huret Allvit that doesn’t seem to have the spring strength to pull the chain down from 1st or 2nd gears. I have the limits set correctly. I believe I have the tension on the cable set well. I have to nudge the jockey cage to get it to drop off the gear, and the tension in the housing just backs up. I don’t see a way to set any spring tension. What am I missing?

 

[twojs.bike]

The only variables I can think of are chain length or derailleur hanger alignment. Do you have an alignment tool? How hard would it be to add a chain link? (Or move the wheel forward as a test)

I’m just making a guess.

 

[CRASH]

I think it’s just the return spring it worn out. Been stretched out too many times in the last 57 years

 

[GeePig]

Unless that chain is drooping between the derailleur and the front sprocket, it looks like the chain is a few links too short.

 

[pacebicycle]

The pulley-cage tension spring has those obvious 2 or 3 settings, but the parallelogram tension spring, which is related to the problem here, is not adjustable.
However, the pivots are adjustable, and I suspect 1 or more of them are adjusted too tight--and if loosened a little, will permit the spring to pull the chain onto the smaller sprockets just fine. The 9mm-head bolts are threaded into the parallelogram arms, then into the locknuts behind them. The play is adjusted just like the double-nuts on the centerbolt of a sidepull brake. It might be easiest to take the derailleur off the bike to adjust it. Unless the spring has been bent or abused somehow, it should have enough strength to work OK, if the links pivot freely as they should, and the cable (both inner & outer) is good. A little well-placed oil always helps too.
In your first pic, it looks like the cable is clamped incorrectly. In the 2nd photo, I can't tell; maybe it's been corrected there. It should go right thru the little hole in the top of the special folded-over washer. If it's not clamped correctly, that will also degrade the shifting.

 

[pacebicycle]

Like someone else above mentioned, the derailleur (usually at the hanger-tab) might be bent inward some. Viewing it directly from the back, it's usually easy to see if the 2 pulleys are in the same plane with the sprockets as they should be, or bent as is common from falling over, etc. It looks like the parallelogram isn't extended very far to be on the inside gear, so maybe is is bent a little. The chain length looks just right to me, for being on the biggest sprocket (assuming it is on the only -or biggest- front sprocket.)