recently i bought nc30 in decent condition, it was sitting in garage for about 6-8 months so first step was fresh oil, fresh fuel, charge battery etc. but when i get to spark plugs ...wel there was huge suprise waiting for me, spark plugs ware bearly screw in, i was able to unscrew it with my bare fingers, and everything was covered in black oil:

any idea whats going on, or what went wrong?
cheers