when you are going to do shaft alignment you have to check soft footness and than do soft foot correction. Loosen the base plate bolts and check any gap in the front and back side base plate bolts . You can check by feeler gauge any gap . Then insert required shim in the gap. It can be angular soft footness also . in this case you have to use two shims of different thickness as per gap. If you will not correct soft foot the reading will change after you tight the foundation bolts . So it is very important that you make soft foot correction .
