Ok. Not to worry then. It doesn’t really “do” anything to the machine, except to make it more versatile. It’s just a matter of taking some parts off and replacing them with others. I don’t see that it harms the machine at all. And you can swap power systems back and forth whenever you like.
I have one on my FW, and really like it. You could think of the handcrank as just another attachment like a buttonhole attachment that can be put on or taken off whenever needed. It gives the user an “either or” choice of two power systems.
It’s great for taking to Quilt Shows to piece quilt blocks. That’s what I use mine for mainly, but it is also handy for use with children learning about sewing on a machine, for use nearly anywhere that electricity is not available, or for not having to plug-in when only a few stitches are needed for a repair.
CD in Oklahoma