harmonic balancer

i have a 360 and the balancer is wobbling. it was a new stock style replacement . i think i need to replace now it but i dont want this to happen again so what quality of a balancer should i be looking into? the engine spins as high as 6500 rpm. this was a perfectly good balancer when i installed it but as time is going on its getting worse and worse. the engine icomponants are balanced as a whole so if i change out the balancer with a new/different kind will that screw up the balance work done by the machine shop?