If you find that the play is all in the servo bushing, you can replace the covers with s3004 covers. The only difference between the two servos is that the s3004 has a ball bearing. Tower sells a kit to convert 4 servos for not much more than one s3004.
http://www3.towerhobbies.com/cgi-bin...?&I=LXXD61&P=7