My Kodak Brownie Starmatic is showing its age

I put a roll of Shanghai GP3 100 film through my Kodak Brownie Starmatic not long ago. I was testing this film before I committed to using it next 127 Day, coming up July 12. Along the way, I discovered that my Starmatic, now 67 years old, has a hitch in its getalong that affects the images. Let me tell you about the film first. It appears to have a decent range of tonalities and good contrast. It is said not to have great dynamic range. Perhaps my Starmatic’s primitive automatic exposure system was doing good work, because my images all came out well exposed with minimal blown highlights or crushed shadows. Helpfully, it was a full-sun day. Pro tip: when you develop this film, pre-wash it several times until the water runs clear. There’s a blue anti-halation coating on the film that apparently won’t interact well with your developer. Looking around the Internet I found people liking this film in Rodinal 1+50, so that’s how I developed it. The Starmatic, with its selenium meter and…