01
Describe the carrier
Photograph the outside of the cassette case or record sleeve without opening unfamiliar assemblies. Note the number of sides, stated speed and anything you remember about the recording. Keep a damaged carrier separate and do not repeatedly play it to see whether it improves.
Mould, a damaged shell, loose tape or unusual resistance needs specific attention. Avoid household cleaning products and improvised heat treatments. A transfer service should not be confused with conservation of deteriorating media; some sources need specialist handling first.