You checked your Minox and it passed the shutter test. The times run plausibly, which means that longer times open the shutter longer than short times. So far so good.
So are the times correct? Of course not necessarily. “Dare to know” Kant tells us in this context.
So let’s measure the shutter speeds of our Minox. But how? Most methods send light through the lens and measure the opening of the shutter through the open back cover of the camera. Oh no, not with a Minox! But yes, it works. Read my simple method to accurately measure Minox shutter speeds here.