How do you replace the crankshaft position sensor on a 1996 Buick Skylark 3.1 V6 Limited?

I had this replaced but I believe the mechanic damaged the harmonic balancer in the process...I was told that you have to take the balancer off to replace the sensor...if true the mechanic replaced the bad balancer and I went back the next day for that...or he broke it and tried to hide it.How do you replace the crankshaft position sensor on a 1996 Buick Skylark 3.1 V6 Limited?if the place you took it to gave you a warranty then they have to fix what ever it is id go up there and talk to the manager if there is no warranty id still go up there and talk just not as nice