Why does my burner scratch the disc?

I use leading brand DVD’s but why does my burner always keeps scratching the disc after burning a few times then its not usable anymore.

I bought a DVD laser cleaner from Maplin, it doesnt work, theres only a tiny brush on the under side of the disc and a few .vob movie clips. I feel like i’ve been ripped off.

I do not think it has to do with laser lens.
Look at the scratch the way it show on DVD.
If it is from inside out than head could have something on it when it moves back to start it scratch DVD.
If it is radial, than there could be something on the tray or inside.
Either way I would take burner out open it and inspect, instead of using commercial cleaners.

If you can’t find an obvious problem, ditch this drive and get another. DVD burners aren’t terribly expensive these days…depending on your location of course. But it is a better solution than scratching all your disks.