I am unable to play pre-recorded video tapes, as there is "graining" showing on the screen. I have tried a head cleaning tape without success.

Hi

Grainy pictures on pre-recorded tapes played on your VCR is a symptom of either

1) Dirt and static build up on the playback head inside the VCR. (see below)

2) A fault within the playback head itself. (will require service replacement)

3) Tracking control improperly set - (This can be adjusted either via the menu options on your VCR or using left and right tracking buttons on the front of the VCR)

4) An improperly aligned playback head (will require service adjustment)

4) An improperly tuned TV - retune TV to video output channel (if your VCR is connected via SCART this does not apply)

As you have already used a head cleaning tape with out any success the only other option to remove stubborn build up is to open the VCR and clean the head directly with an alcohol cleaning solution and a soft chamois tipped stick. This will often resolve the issue but you need to be careful during this process.

A very good How To Clean Your VCR Heads can be viewed at this link http://hometheater.about.com/cs/vcrs/ht/vcrheadcleaing.htm

As always when opening any electrical appliance - ensure it is disconnected from the mains supply to avoid risk of electric shock.

If you find this problem occurs only with pre-recorded tapes and the VCR plays back its own recordings well - this is a strong indicator that the head is misaligned as per point (4) in my answer.

Hope this helps. Please remember to rate my answer. Many Thanks.