the stock balancer last around 120k-150k miles and is relatively cheap ,
you can have it rebuilt for $100 almost the cost of a new one. well close anyway. I rebuilt mine at home cost $15 BUT MOST DONT HAVE THE TIME OR SKILL TO DO THIS .
mine is going 5k since I did it. best way to preserve it? well dont start engine up make sure all bolts are tight, and you shoud be ok for over 100k miles.
things break when loose if it goes on easy its bad a snug fit is the clue to a tight long lasting balancer its alluminum if its loose replace it the hole is already worn out of round and will wobble and cause failure.