Steps from landing to top floor need to be the same plus or minus 3/8" max 7-3/4" rise.

Do all the steps have the same rise or is the top step shorter?

"Thinking we will have to tear out the staircase and start with new stringers."

If you're at 7 3/4" risers now, you'll need to add a step which requires more run which you may or may not have.

The balusters on the handrail don't match those on the guardrail and appear to be spaced more than 4" apart. This whole thing smells amateurish.

You need a new staircase.

I'd first check with your local building dept. on the maximum rise. Many local codes allow up to an 8 1/4" rise. If you want to get out of this on the cheap, you might be able to add 1/4" to each rise, 1/4" first rise, 1/2" to the next rise. 3/4" to the next, etc. You will have to modify the skirt boards for aesthetics too.