TellyOne

Some possible cause of lines, noise or pixelation during playback are:

Dirty heads on the recording machine. If the heads were dirty at the time of recording, the dirty heads didn't record a strong enough signal on the tape. The damage is done for this tape and recovery is unlikely. Best advice here is to use only premium grade new tapes and keep your camcorder clean by occasionally running a cleaning tape.

Physical tape damage. Any distortion of the tape will result in mistracking and subsequent loss of data.

Built up oxide deposits or other debris in the guidepost corners can also result in tape edge damage. Keep your machine clean!

Improper tape storage - Even short term exposure to high temperatures over 130 deg f. can permanently damage the tape. The black cassette housing readily absorbs the sun's infrared rays and internal cassette temperatures can soar even if left in direct sunlight on just a warm day. It doesn't take much heat to slightly distort the plastic shell or ruin the tape contained within.
Try other tapes to ensure the problem lies within the tape and not the camcorder.
If the problem becomes apparent on all tapes, try a head cleaner. After cleaning the heads, the tapes may not play cleaner if the recording was done while the heads were dirty.