one of my cdj 400 is not reading cd anymore writes on the screen 8303 audio,mp3 any format tryed to clean the disk it self but didnt work at all, my cdj never fell off,,, a dj tutor on youtube said it may be some dust on the lense try cleaning it with a lense cleaner u know the cd with a small brush...
what should i do?
m only using usb flashs on this one m unable to use cds

The lens cleaner discs can cause more problems than they solve, they can damage the lens' suspension arms.

Take it to a repair centre or at least someone who repairs CD drives and ask them to clean the lens.
Error 8303 is related to the mech being unable to read the CD, normally a focus error.
This is normally caused by a dead or dying laser.

bought them 6 months ago how cloud the lense die or be so fragil + plus pioneer product are normally solid

Well, if you only bought it 6 months ago, it's still under warranty. Contact Pioneer technical support for Europe / Africa from the links at the top of this page.