Turbo_Tkk

hey i have a impreza turbo 2000 1997 classic
im ahving a problem with my crank pulley.
it got a bit of play in it.
as in when the car is started the puley shudnt move back and forwards.only in the clockwise or anticlockwise (what ever way it goes). but i'm having the pulley moving a bit.

About a year ago or mayb more the pulley broke off and i replaced it but the key that goes through the crank shaft,gearbox.
the key tip which goes near the pulley was a bit damaged as the pulley rubbed against the tip of the key, so im finkin it might be somthing to do with that????

im a bit lost and worried so i would like to no what could i do?
please pm me or rpely back to me im new to a impreza my first one.

What can i do???replace the pulley, or the key or do i have to do somthing even more bigger???