Pete, get some sleeping pills. Your are always going to have a small amount of play. The tolerances for ball links are not that tight and the gear train slop in the servo all add up. You can expect to see from 1/16" to 1/8" play in your stabs. Relax you wont notice it while flying. The F-15 is not a fast jet as it has it lot of intake drag. The geometry of the stabs magnify the small amount of play in the linkage. The YA jet is a very nice kit and flyer. Have fun. Dealing with Shaun is always a pleasure.