pegasixi:
The current setup does something quite similar: It uses a tensioner to pull all three sheets (kinda like what the weight would be doing in your scenario). Unfortunately, using gravity is not an option due to the machine's stupid layout. So... instead of letting gravity do the work of aligning it, I have to find a way of manually lining everything up
Is the tensioner based approach not working, then? I'd have thought that was your best bet. Trying to detect tiny alignment errors and then compensate for them (how?) feels like a much harder problem to solve.