My dad has given me his old Olympus OM10 film camera but he isn't sure if it works or not. The winder won't push forward fully but the camera has no batteries in it. Should the winder be able to push forward anyway? Is it most likely broken or does it just need batteries?
Is it most likely broken or does it just need batteries?
Try pressing the shutter release button. It could be that the shutter is already set, so the camera just can't be wound any further. If you hear the shutter trip when you press the shutter release button, you'll probably be able to move the film advance lever again.
Another way this can happen is if there's film in the camera and you've reached the end of the roll.
The manual(PDF) also suggests checking whether the self timer is engaged. It does also say to check the batteries, but I don't think a flat battery would actually prevent you from moving the film advance lever. The film advance is a mechanical system, so you mostly want to think about mechanical causes.