Once Cleaning up the spec and the changed/removed styles are fixed, you can compare the old and new versions of a Part using the W3C HTML diff program. The following links use that tool to compare trunk with the current tr35/
You will need to manually set the encoding in your browser to UTF-8 (and the tool still doesn't get it quite right). The w3c tool has many false positives (<pre> and <table> often fool it) also, so you will see cases like:
But it should allow you to double check that the Modifications are correct for your Part.