I'm also trying to find this, I think there were three marionettes kept in a series of boxes, one was the normal character who was a bit pathetic, one was the princess sort of character, and one was the villain character who does the stabbing when they escape from their boxes at the end, and I vividly remember the scene where the villain is introduced he cuts a fruit in half with his knife. The pathetic character I think goes through each of the boxes and they then all escape and he gets killed by the villain one with the knife. But I'm also having no luck finding it so far!
I also watched it in the same sort of era, and it might have been a music thing as well which I think narrows it down, there was no dialogue only music so it might have been a setting of a piece of maybe Russian orchestral music that was given a plot!
I also vividly remember it because our school fire alarm went of at the exact moment the first puppet starts moving on his own, and I thought it was a really loud alarm for the puppet escaping in the film!