Canon video camer ZR700

No, it cannot.

It is not possible to play directly on this camera as it is an old model.
You should get a cassette player and put the tape in it and connect it to your TV.

That is the pinch roller. If it does not press the tape against the capstan, then the tape will not pass the read/write heads. Replace it.

Clean Idler unit it is magnetism and clean sensor it will work

Playback no picture? Try to clean the head by inserting cleaning cassette. During camera mode, i don't know if you see anything in your monitor. What you see is what you can record on tape so may be your problem starts from here, please elaborate more.

CONNECT THE CAMERA VIA THE DV -4 PIN CABLE TO YOUR PC ON THE FIRE WIRE CARD -
INSTALL THE CANON DRIVERS FROM CANON WEBSITE
USE A VIDEO SOFTWARE LIKE ULEAD OR WINDOWS MOVIE MAKER
MAKE YOUR CONNCECTION ON THE PLAY MODE AND PLAY THE MINI DV
BEFORE THE PREVIOUS QUOTE MAKE THE AV-DV OPTION ON IN YOUR CAMERA SETTINGS
ALL THE BEST

If there is no problem when you play back on a different camera or computer, then the fault concerns LCD ribbon cable or lcd controller circuit on main pcb.

If the recorded image is also distorted on computer and different camcorder, then you have a faulty ccd sensor.
Also wiring problem and pcb fault sometimes can cause ditorted picture, in that case the problem is usually a kind of dirturbance and does not happen all the time.

Regards.

Does the black line record on the tape? When you play back on a TV/Computer can you still see the black line. If you do that would be the image sensor.
Good luck!!

The monitor you view while recording does not read from the tape where the problem is located, that's why you are not seeing them during recording.
Since they are not visible while recording, the video section is healthy, only the recording is faulty and it is unlikely you can do anything at home to correct it.
This may be a common problem and perhaps Canon is familiar with it.
I recommend you call their service line directly:

email: https://www.usa.canon.com/consumer/controller?act=SupportMailerAct&fcategoryid=227&modelid=12812

Phone: In the US: 1 (800) 828-4040