Have you taken the base plate off to see if the wind coupling/rails to guide the trigger transport are still in place?

If it is then I would suggest someone removed the trigger mechanis because the ribbon was broken. The top looks original VT, and you couldn't remove a lever wind and replace it with a know, as the know turns in a dirrerent direction to the lever..

I used to repair cameras at Canon, and have collected them on and off for years. I think this is one that was broken and had a new base plate put on to it...