Installing harmonic balancer/crankshaft pulley on a MSP

I get a vibration only when idle and when I get on it hard it will stay idle at 60 or however fast I am going only for a lil while. I also noticed that the groves were slightly rusted and the teeth were a lil bent some of them therefor edge of belt a lil rip but not enough to whine 24/7. Watched a YouTube video on installing this part seems straight forward but dosent this effect timing the belt as we'll if that's the case i rather not mess with it unless it isn't that difficult. How the f... Does this part even go bad I would have never thought the teeth's would even bend pulley part ok wear and tear over years but that's weird.