Yashica FX-3 super 2000 auto-fires when advancing the film

Hi,

My Yashica film camera has just started to automatically release the shutter as I am half way through advancing the film. If I advance the film very very slowly, I can sometimes avoid this happening but not always. I find it also helps if I set the shutter speed really low before advancing the film.

I wonder if there is anything which needs loosening? It is strange because I have had it for years and not had a problem before. The film is then moving when the shutter is opened so the photos are not full frame and have motion blur.

Any advice would be greatly welcomed, thanks!