Hitachi VT-UX615A Owner's Manual page 82

PROBLEM GUIDE/MAINTENANCE
the heads.
Note: Mechanical sound is hear during head cleaning.
NOTE: Dirt accumulation on the video heads will cause the playback picture to become noisy.
Heavy accumulations due to abnormal usage, or the use of poor quality tapes may be
beyond the capabilities of the Auto Head Cleaning System, and may require the video
heads to be professionally cleaned by a qualified service dealer.
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