You can request replacement parts for your Ultrascope or Maxiscope through the Lifetime Warranty page of our website. The only part unavailable through there is the acrylic bell which should never need to be replaced. If there is a particular issue with the bell itself that cannot be solved through information on the Troubleshooting page or with a replacement Diaphragm & Retaining Ring, you may need to send it in. Please contact us before doing so as we may be able to help you figure it out.