If you want to start up a business in repairing dental handpieces, then you're at the right place. You can make up to $50 to $100 per delivery. You won't have to do face-to-face selling. You'll make and get phone calls. When you get that phone call, you just go pick up the piece or pieces that are needing to be repaired. Then you can ship them to a wholesale repair depot and they'll usually fix them in a day or two and send them back and you simply deliver them back to the client. You can get this "business in a box" at this website.
You can do something similar if you can repair it yourself, you can still pick up and deliver, but you can purchase the supplies yourself to fix it and make a profit. At websites like this, you can purchase parts so you can fix things yourself. On this website, you'll find items like this to purchase:
They have everything you need from back caps and wrenches, handpiece gaskets, and quick connectors, to repair shop tools, turbines and cartridges, and bearing service kits. They have any part you would need to fix dental equipment.