I've taken a photo, but it's not very good, having been taken on a phone. I've arrowed where the problem is. I press the tape down with my fingers, but often, when I look after the splice, part of the film has no tape. Often the area is larger than shown here. Looking at the cut, where the tape is still connected to the roll, it looks like the tape is torn rather than cut, and maybe that explains it. Perhaps it would benefit from trying to sharpen it.
CIR.jpg - Bild entfernt (keine Rechte)
Going off track a bit, but most of you here are too young to have heard this. In the late 60s, when men were buying packets of razor blades, there was some tip about leaving a blade out overnight and have it facing north, and the magnetic pull is supposed to have sharpened it. I never tried it myself. I don't know if anything else was involved. Then another trick was wetting the inside of a tumbler with water and rubbing the blade on the inside of the glass, I did that a few times when short of money.