Notes are not up to scale.

So your mechanical leader and notes are behaving badly and not scaling to the viewport scale. Bad notes, bad... You either need the notes whisperer or set a couple of variables to neuter these issues. AMSYMSCALE sets symbols (ie Notes) back on track and AMRESCALE gets your existing notes to behave. Whew.. good notes, good.

Isn't that special.

Or should I say "that isn't special". The special characters in the dimensioning mode show incorrectly. The diameter symbol for instance looks like some weird text. Well this is a Window Font issue. Look for the AMGDT*.ttf fonts in the Windows\Font folder. If they are not there, copy them from a working computer or do a repair install of AutoCAD Mechanical and you should get them back. Congratulations, you are special again.