A friend asked me for help, as there have been some changes in the formatting that scrbook provides, which is not good for an updated edition of a book.
Currently, I am tweaking his sources in order to have the pdf look similar to the old version. Particularly page breaks should be consistent.
Mainly the chapter headlines seem to have changed (also the itemize parsep...) such that there are ending points in the numbers and the font seems to have gotten wider but thinner. Also the parsep after a headline has increased significantly. See pic (where I already removed the point).

Does anyone have an idea how to get to the old look for the headlines?
A simple
\setkomafont{disposition}{\bfseries}
has no effect. Seems that this should already be fat...
compile output for the versions i use right now:
This is pdfTeX, Version 3.1415926-1.40.11 (TeX Live 2010)
...
(./master.tex
LaTeX2e <2009/09/24>
...
Document Class: scrbook 2010/06/17 v3.06 KOMA-Script document class (book)
please don't ask for the old version, i have no clue.