Superdrive won't mount disc's

Hi,

I do not use the built in superdrive on my mid 2010 iMac very often but I have just discovered that it will not mount a disc. I can hear it trying to mount but it fails, both DVD and CD. I have been looking on-line and can see that many people have had issues after upgrades to OSX. My Mac came with Snow Leopard and I have upgraded with each new incarnation and now run El Capitan 10.11.3. Unfortunately I am not sure when it stopped working possibly after Yosemite upgrade?

Anyway is this a software issue, firmware issue or breakdown?

Any help appreciated.

Thanks.