A4 models ADF rollers/feeding are terrible(any manufacturer). They aren't made for a lot of scanning. Regardless of counter rubber wears with age just as your car tyres. Generally speaking newer machines rollers are way more reliable, I remember analog Toshiba rollers went slick as F1 bolid tyres after 80k pages and even before if the paper is cheap cr.p. Today KM rollers frequently outlast their oneways/torque limiter. Nuff said.
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