Recently took possession of an Otari MX5050 reel deck and noticed that the
heads and other tape contact parts are rather dirty. This is a rather old
unit and the "dirt" seems likewise.

This substance is a brownish colour, and not only dusty but chunky. I've
tried a moderate cleaning with 99% Isopropyl alcohol and Q-Tips. I've had
some success, but the "chunks" are real stubborn.

How do I properly get the chunks off the heads? Does this dirt pose any
threat to my tape?

Thanks for any advice...

JK.