You should have all the paperwork with you that came with everything and call the company bout parts and service and explain that your magnet is broken and you need a new one. My computer was broken and I called the company and they sent me a box with a new one and I had to send my broken one back to them via UPS. No charge. Labels and everything where included.

Talk to your Dr. About the replacement for your VNS magnet

I lost my magnet. I have a friend who is a veterinarian. Vets have magnet for livestock. About the size of your finger. Get one at a vet's office. Cheaper

The best thing to do , is talk to and ask your Dr. About it.