I've fixed/flipped/restored a lot of bikes, mostly vintage, but sometimes I run across something that I feel like I should know but don't.
I done many 20-25 French restorations, but the Simplex stuff is usually toast and I replace it. And eventually the French bikes started shipping with Japanese parts. This derailleur looked good, but I can't get it to behave. The top pulley is too close to the freewheel. It handles the low cog but it can't move up/inward without crashing into cogs. If I hold down the pulleys, second photo, I can shift up to the large cog. I don't see a B-screw on this design or any other way to push the pulley cage down. And btw, this Simplex RD came on this bike! But I disassembled it a decade ago and hung the frame on my wall for a future build.

I think I've read others having that problem but never seen it myself until today. I had plenty of Suntour RD's but mistakenly donated them to MikesBikes Africa drive, and they are long gone. I've got two choices: this Simplex and a too-modern looking Acera, hardly the right thing for a Peugeot Mixte. Still, if I have to...
3rd choice, there's a swap meet Sunday morning, if I'm still stuck.

Idea's?