digital – What team did film photographers obsess over?

I found a box of old camera things in my brother-in-law's house while he helped them move and made me think: "What team did film photographers obsess over in the past?

For example, with modern digital photography, the sensor seems to be the most expensive and sensitive part of the camera body. Keeping it clean and safe is essential for good photos. There are countless online articles and instructions to clean, maintain and prevent sensor damage. However, with a film camera, the image surface is not a very expensive part of the system. Scratching the film would ruin your photo, but it would not ruin the body of your camera.

So what do you think, what equipment and maintenance questions do you think would fill the forums in the past?