I'm a woodworking beginner trying to restore a Stanley no 5 and have run into problem with the blade hanging lower on one side.

I'm not sure if it was originally like this or something I did - I've flattened the sole, squared and sharpened the blade, and ran the frog over sandpaper a few times to remove dirt.

There are no noticeable issues with the mouth, it looks nice and square. 

I think this may be something to do with the frog?
Any ideas?

[![enter image description here][1]][1]

  [1]: https://i.stack.imgur.com/1xpZQ.jpg