needs help here bearing problem

i notice that everytime i run my bike the side cover where the magneto is, is always getting wet , gas is leaking, i took out the magneto and the magnet as well, i saw the black o-ring at the end of the shaft, i took the o-ring out and i saw the bearing inside the crown is broken and 1 missing bearing. does anyone know how to take the shafting out, i think the connecting rod is attached so i might need to take off the cylinder head . is there somebody has a diagram showing how to dismantle it. although my bike is still running good seems like there is no problem at all when you ride it, just the leak from the o-ring and the broken bearing is my problem,
is the bearing replaceable

its crankshaft bearing. just like this picture .hope i can find replacement for this. is there a way to take this bearing off?