Has anyone ever seen a harmonic balancer key way wear out before? and for  replacement I was thinking about an aftermarket light weight pulley any opinions on that? Figured since it a boxer that there would be no need for a balancer and instead just a pulley... I seen a topic on dirty impreza about using a light weight pulley just was wondering on some more opinions on it 

that happens when the crank pulley isn't properly torqued. its a common problem

Very common, the crank bolt comes loose and the pulley starts wobbling and beats itself up.

 

Plenty of people run the one piece pulleys. Just be sure to get the bolt good and tight or you'll have the same problem again.

Okay thanks, what's the best way of torquing it if it's an automatic?   

A 12 in long screwdriver through the flywheel inspection port will hold the crankshaft.  I put 130 ft lb on the bolt even though the 90's subaru spec was less then that.

Big screwdriver or prybar through the inspection hole, or a the largest hex key or screwdriver that will fit through one of the holes in the side of the bellhousing.

got it, thanks!!

Beer Garage has a pic (with the engine out) showing this.  Way easier to access from the passenger side (as shown in the pic) as there is more room and some hoses to dodge.

http://beergarage.com/imgs/Suby/Lift/13.jpg

 

the keyway isn't need - torque that mojo down and the pulley will not back off.  it's iron crank so it's not aluminum and not prone to strip like much of the motor. 

 

i've got a one piece on as well.  no big deal, just bolt on and go.  i noticed zero difference in performance with it.