you can't damage the bearings, they're made of steel. maybe you could damage the cartridge itself though? i'm not sure. you won't be able to get proper adjustment though if you don't have two wrenches, or at least a headset wrench and some channelocks (use a rag so as not to ding up your nice headset) the previous post is correct about adjustment, also check the parktools link i posted earlier, there's a section on proper adjustment. it's a finesse thing, you want to make sure you have maximum spinning without any forward/backward play on the headset. good luck.