How old is the Grado? If it's old, the suspension is probably pretty stiff and that will definitely cost you a lot of the highs. There's nothing wrong with the turntable, although you might want to find out if that model has a muting circuit (some did) and if it does, it may need to be checked out.
Check out the Denon cartridges- if you have a moving coil preamp, the DL-110 is a lot of bang for the buck and the high end is nice. I had an old DL-103d for a long time and while it still works, its suspension is old and with my new DL-110, the highs came right back to normal.