In article , Lobster davidlobsterpo
writes

Is it OK to touch the faces of the rollers or does that damage them?

Try not to. If you have latex gloves, wear them. Skin oils burn on the
face of the rollers and can damage them.

Can't get any purchase anywhere otherwise to try moving them, to check
whether they are jammed...

You need the big gear - the broken one

--
Mike Tomlinson