I have this microtome.  I love my microtome (Olympus Cut 4060).  I too have 
had this problem.  If you will slide the knife holder plate on the front to 
one side, it will expose a screw.  Get your tool kit that came with your 
microtome.  When you adjust the screw it might feel like it is tight, but it 
probably is not.  Move it back and forth kind of to know exactly which way 
you will need to adjust it.  What has happened is that this screw has moved.  
It is too low.  Raise it and you will feel it tighten slightly.  Move your 
blade holder back into place and check to see if the tension feels right when 
you tighten down your blade (to get the proper fit, you need to have a blade 
in the holder).  You will know when you have it right.  Mine had this problem 
quite often, but it has been a while since it has occurred.  It seems that 
when this other tech uses my microtome, she is more aggressive than I am, and 
I think that is what makes this happen (I could be wrong).  I hope that this 
helps.    It always works for me.

Jeanie Wade, H. T.   (ASCP)
Pathology Associates of Tyler, TX