How to avoid chatter (Venetian Blind effect/washboard/undulations)? FAQ Report The clearance angle is too big: Clearance angle adjustment; systematically decrease the clearance angle until the optimum adjustment is obtained. A damage to the pressure plate exists (bent/nicked): Replace the pressure plate. An insufficient clamping of the blade, the knife holder, the specimen and/or the orientation might cause this problem. Please check the clamping points and repeat the clamping of levers and screws of the specimen and knife holder system. Check the front pressure plate for wear. If the round on the lever is worn, then replace the lever. You might use incompatible blades. The blade is possibly too thin, causing flex if the specimen is too hard: Try using a different brand or grade of blades. The high profile knife may be too thick: Try using a different brand or grade of blades. Wax is built-up on the back of the front pressure plate: Remove and clean the rear of the pressure plate. It might be an application issue, not a microtome problem: Infiltration, dehydration, decalcification, paraffin is too old, paraffin impurities. It might be a problem of the tabletop stability: Move the microtome or table to a more stable location, or replace table if table is flimsy. There might be vibrations in the specimen advance system: Check if orientation has been changed or incorrectly disassembled. Re-install all parts, if necessary. There might be a too high sectioning speed: Decrease the speed.