RE: Draw weight?
Beyond trying a different scale, did you checked your ATA, brace height, and cam timing after putting on the new string? After a year of shooting you need to check all of that.In reality that should be checked quit often.
If the ATA is long the limbs are not loading properly and the DW will be lower. Your ATA could be on but your brace height off. Again, changing the DW. Even a shop can't simply put a string on and have everything correct from the beginning.
One other point, did they put on the correct length of string. If not, it wouldn't be the 1st time that has happened in a shop.