timingbelt riding off center on gears

[KGWilder]

what would cause the timing belt not to ride on the center of the gear , too tight or something else this issue is from a 2.4 liter 5cyl that I replaced the timingbelt on a 2009 S40 I REPLCED THE WHOLE ENGINE I didn’t know how old or when if any the belt was replaced so I did to be safe , I haven’t had a car for 4 months n im done but not even going to start it with this problem would be fatal, if came completely off, any help would very appreciated , thanks.