Agfa Billy I 6x9 folder.

Hello all! I picked up an old Agfa Billy I folder with a Agfa Agnar 1:6.3 / 105mm lens.
My question is if the focus adjustment ring is supposed to be used while turningthe front knurled ring. This one seems to be blocked (old grease?).
There is a stopper underneath that I gather should allow one full turn from +/- 1m to inf.? Thanks in advance.

Agfa used this green grease on some of its lens helicals that, when dried out, turns hard as a rock and prevents many of their lenses from focusing.

BobD, Thanks!