i think they were the brass... the trans hasnt been in the car that long.
it does look like one is wore more than the other. maybe the shift fork is bent causing misalignment.
you need a case that has "windows" in it so you can see it all assembled and take some feeler gauges and measure if its engaging evenly. then you can either get another fork or monkey around with the pads to compensate.
making a jig may be a better idea though. a tight fit rod that the fork rides on with a perpendicular surface attached to it. slide the fork over the rod and measure straightness.
Brian