Panasonic DMR-BW780EB Service Manual page 51

Service hint
If a defective phenomenon is "NO READ", please try to clean TT (turn table) in the drive in according to the following procedure.
1. Blow off dust on TT by a blower. (Air must not blow to it strongly.)
2. Apply one drop of ethyl alcohol or isopropyl alcohol on a clean cotton swab.
(Always use a fresh cotton swab free from any additive or chemical.)
3. Lightly put the cotton swab on TT, and wipe it by turning by your finger.
(Don't touch the surface of TT when you turn it.)
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