Doug;
I have never heard of reaming with respect to replacing injectors and have never done that myself. The Mercedes shop manual makes no mention of reaming and does not include a reamer as one of the "special" tools needed to install an injector. Replacing seals is not a bad idea although I don't always do that myself.
Ken

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K. Weimer
300SD (1)
300D (5) [Plus 1 parts]
300SEL 4.5 (2)
280SE (4)
280 (2)
250 (1)
250SE (1)
240D (7) [Plus 1 parts]
220D (11) [Plus 3 parts]
200D (2) [Plus 1 parts]
180c (with sunroof)

1995 Nissan UD1800 rollback
"If I can't fix it, it don't get fixed"