imac 27" superdrive never works and scratches the discs

Is it just me?

I have rarely used my superdrive to burn CDs or DVDs since 2009, and whenever i have it is always going wrong.

The disc/drive makes a horrible noise, and ends up scratching the DVD or CD.

Now when i need it the most to burn a dual layer DVD it won't even mount the disc to burn to it?

It just makes awful scratching noises, and then it takes me 20 minutes to try and eject the bloody thing, what is this all about?

Can anyone shed any light or have had similar experience to this? it is a late 2009 27" iMac 2.8 ghz Intel core i7 running 10.9.5

Do i need to buy an external DVD burner, and if so what should i go for?

Thanks