I must concur with Bob.  Because different manufacturer's require different
knife angles it can sometimes be confusing when folks switch microtomes.  The
manufacturer setting for the Zeiss/Microm is at 10.  It shouldn't vary much
from there or you will get the artifact you describe.  Also make sure the
specimen clamp is secure.
Please let me know if this helps.

Dawn Truscott, HT(ASCP)
Carl Zeiss, Inc,