Roland GR-640 User Manual page 91

Procedure
Remove the separating knife.
(1) Loosen the screw until it slips out.
(2) Grasp the screw portion, and then slowly pull it
out in the direction of the arrow.
When doing this, do not pull it back toward you.
Install a new knife.
The knife is secured in place by the magnet.
1: Magnet
2: Positioning groove
Slowly insert the knife into the groove.
Tighten the screw.
Take care to ensure that the knife does not slip out of position at this time.