Could be tracking, dirty / faulty heads, or mis-alligned guide rollers.
First,adjust the tracking on the player during playback. This is done by pressing P+ or P- on the remote control.
If this doesn't work, use a video head cleaner. This consists of a video cassette and fluid. Follow the instructions with the cleaner.
If this still doesn't help, and you are confident in opening up the VR550, you could cleaner the heads manually.
Disconnect from the mains.
Remove the screws from the back and sides of the VCR.
Gently ease the lid off the machine.
Locate the large silver coloured head drum towards the back of the machine. There are four small receptors around the side of the drum. These are the video heads.
Take a small piece of clean white paper about 1.5 inches square. (Copier paper)
Hold the paper square over 1 finger and rub each head in turn. Keep the head near the centre of the paper so as not to catch the heads with the edges of the paper.
Check the paper for dirt from the heads.
Reconnect the player and try a tape. If the problem is still there, try cleaning again.
If none of this works, insert a tape NOT recorded on this machine (Mis-alligned rollers affect recording as well as playback) and play. Locate the rollers which guide the tape around the mechanism. Particulary either side of the head drum.
The rollers have adjustments on the top, which can be turned to move the guide up and down slightly. This is a fiddly job, and over adjustment could cause the tape edge to be damaged.
Adjust the rollers to get a clear picture. It is mainly trial and error.
If all fails then the video is probably destined for the skip.
If you need a replacement, www.cheapestelectrical.co.uk
, will sell you a VR550 at a very good price.