ghostrider

So how does the machine manage to sew in reverse??

I've unthreaded a wide variety of sewing machines in the many decades since I first learned to use one. In fact, I've never once cut the thread and pulled it from the bottom. The tension only gets "messed up" if you pull backwards on the discs when they are engaged...in other words, when the foot is down. If the foot is not down at the time, it doesn't matter if you unthread your machine frontwards, backwards or sideways.