Piepatch,
The hardened white stuff could have been white lithium grease or some other stuff.
Singer now makes a grease that is white and states it's for gears. I have some and it's quite sticky. Not at all like the old Singer Motor Lube grease.
However, I use Tri-Flow grease on my 401 and 500s. It's a synthetic and does not harden or run off like some greases do.
I get it from Sew-Classic.
Joe