Unscrew the oiler out of the machine and dig out any hardened gunge lurking down the hole. Flush out with kerosene, degreaser, solvent etc whatever you have handy to clear congealed gunk of ages from the bearing. Likewise give the oiler a good clean out and flushing too.

At the same time clean, replace or make out of felt (if absent) oil filters. Bearing will be grateful for that.

Also dont break these oilers. If you do, you will face a lot of troubles. These ex Adams are expensive but good and cheap imports sold by RDG do not work. You will end up making new or at least making some parts new, unless you get them from Adams.

Matrin

Not sure what they had originally. Some oilers had a felt or wire gauze filter in the bottom of the glass section. At a pinch, a wad of felt down the hole before you screw the oiler in to the lathe would act as a filter.

I have used the cheap Chinese oilers bought online for several years. They don't form a clear, visible drip like a "proper" old time oiler. But with a bit of trial and error they can be adjusted so the level in the glass drops, say, an inch or so over the course of a day of using the machine, which I figure is plenty enough. (In fact more than enough judging by the mess all over the machine!) Trouble is, its hard to find new cheap oilers with the 1/8 BSP thread to match the tapped holes in the lathe. You either have to make ungainly adaptors, or try to butcher the 1/8 NP thread on the new oiler with a BSP die, or just screw the new oilers in the one or two turns they will go in and leave it at that.