A big problem with 8mm video tapes and similar formats is mold. Because the tape is thin this makes the tapes more fragile compared to VHS tape which is far more robust. What will happen with these tapes is when they are moldy, that mold will cause the tape to tension up and snap. The snap can either be a clean snap or a lengthwise tear. This is especially bad for 8mm tapes, as there’s a section of the tape reels that could easily hide mold. Because of this, these tapes require very tedious manual cleaning to break apart the mold.
The video below shows a tape that had such a problem. After not noticing the tape had mold, I queued it up for transfer only to have it break. The issue is, even if you get to the tape before transfer (side note: I now check every tape by manually moving the reels so I can see every part of the reel is clean), when unsticking the reels, the tape still has a tendency to tear. You can also have mold on the underside of the tape, which complicates things. After careful cleaning, you have a clean tape ready to run. The hope is that the tape isn’t suffering from another problem, sticky shed syndrome; if so, the tapes will need to be baked also that the tape isn’t dirty.
A must when doing this work is an iFixit Pro Tech Toolkit. I also recommend using something non-fibrous for cleaning the tape if it’s dirty. I mainly picked away the mold here, but you can also bake the tapes to kill the mold. I would clean them first, then bake. If you carefully stretch each reel out and apply a little tension, you can sometimes break the mold apart. This also required a lot of splicing because you would get to sections of the tape that were stubbornly stuck and would cause the tape to tear.
