The Leicaflex series of cameras are highly complicated, overengineered mechanical instruments, but not without their quirks. yOURS is now 60 years old, and with any precision device of this age, things cango wrong.
Common issues include the viewfinder prism beginning to desilver. The built-in light meter was originally designed to run on a obsolete 1.35V mercury cell. To get it working correctly today, you’ll need either a modern silver-oxide cell with an adapter or a zinc-air (hearing aid) battery. Even then, accuracy isn't guaranteed.
The shutter is also prone to aging. A typical symptom is shutter curtain tension being off, causing speeds like 1/4 second to actually be faster than 1/8 second (you can hear this).