I recently acquired a Voigtlander Bessa from 1929. It works but there's a dead insect into the lens assembly (between the glasses) and some fungus/dust. I'm trying to open it to remove the insect and clean the lenses, so I removed the lens assembly from the camera and started removing all the screws and everything that could possibly be removed. Now I'm stuck: there's apparently nothing left to remove, but the thing won't open. Any idea on how to proceed? I'm attaching a couple of pictures of the lens assembly as it is now (sorry for the watermark...).