Welta’s shutter mechanism is relatively simple, so if you’re comfortable with taking your camera apart and have experience doing similar things, you can explore it. But I don’t have a definitive answer for you — sorry!
These shutters rely exclusively on the mechanical action of pressing down the button (as opposed to a loaded string on other cameras), so it could just be gunked up a bit.
Does it work on slower speeds for you, like 1/30th or bulb?
