Compression sounds good. I would not worry about the carbon, it's dirty in the combustion chamber. Compression is excellent. FWIW My HF compression tester goes into the fuel injector hole.

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1979 240D- 316K miles - VGT Turbo, Intercooler, Stick Shift, Many Other Mods - Daily Driver

1982 300SD - 232K miles - Wife's Daily Driver

1986 560SL - Wife's red speed machine