The British made Epsilon shutter of the 1940-50s has a reputation for being unreliable. All of the variants I have worked on prove this to be the case.
90% of shutter failures normally fall under the dirt and congealed lube category which is easily resolved with a strip down, clean and re-assemble, however the Achilles heel of the Epsilon is the slow escapement mechanism. The cocking lever’s return puts pressure on the escapement and over time bends the mechanism’s housing which makes all speeds below 1/10s sticky.
This particular shutter had also dislodged two aperture blades so a full strip down was necessary.