MFC-240C Printing Issues

[TechnicGeek]

Hello,

Have been using this device for over last 10 years for printing documents with compatible ink.
Typically I print using Normal Quality but today needed to print using Fine Quality for more precise printing.
Some parts of document printed fine but others are smudged.

Last time I used Fine Quality I did not experience this issue.
I never did maintenance like lubricating moving parts, let alone thorough disassembly and printer head cleaning.
I heard the latter one is possible and maybe I should do that after I take care of aforementioned problem?

Thanks