VPI TNT balancing

I�m currently using a VPI TNT 6 HR turntable (JMW 12.5 tone arm) along with a Shelter 501 cartridge. I have carefully leveled the turntable and rack using the small VPI level as well as a longer level (about 18�) just to be certain all is OK. I periodically go through the set up process to make sure that none of the adjustments have changed. So far so good. Here�s the problem � at least I think it�s a problem. In order to get the proper tracking force, the counterweight is virtually at the extreme end of the tone arm. Although I have never had a problem with tracking, the arm is rather unstable when cued on and off an lp. My manual indicates that the counterweight should be as close to the pivot point as possible in order to make the arm more stable. I suppose I could add another counterweight, but I�m afraid that will be way too much weight on the non-cartridge end. Has anyone had a similar situation, and if so, what was the solution? Thanks.