Alright well, i've seen alot of people having problems with there magnets - this is common on Hitachi drives (in all my findings)...this is not to be confused with the "top" magnet inside the drive cover
This is how to fix the bottom one, the common thing is...(with the top off) you'll put a game on the holder and you'll see the laser turn on but no motor movement (you may be able to spin it a fair few times to get it going again properly but it's still a little hard to turn and will "stick" again) - flip your drive over: on the bottom where the motor is there are 3 screws holding it on...unscrew these 3 screws with a very small allen key (the smallest I had in my set was just perfect) - take the motor out.
Now it separates from the part...pull the magnet up and you'll now have 2 parts - from here clean ALL the black stuff from both pieces (clean both pieces throughly)...replace it with some good oil (personally I have oil for a bike, but it's very special...)...stick the magnet back on and turn it a little (there should be no oil oozing out) - put it all back together, whack in a game and leave it for 30 min....all done

gigabite