hi,

what has happened is that when not in use, steam oil has syphoned back from the delivery pipe into the sight glass.

this is due to incorrect 'closing down' procedure at the end of a steam up, and failing to close the left hand needle valve fully.

it is possible that by using a large bore syringe you can remove the excess steam oil from the sight glass from the top if the union connector is unscrewed. however this is often very difficult to do properly.

my own advice would be to remove the whole of the top fitting to all 3 glasses, clean everything with cellulose thinner, and refill the glasses with glycerine once re-assembled. at the same time you can check that the needle valves are not damaged and that the jets are cleaned and replaced. it would be very unusual to find a blocked jet in my experience.

cheers,

julian