The upper v-rail requires lubrication every 2,000,000 revolutions of the z-shaft. Use only standard sewing machine oil to lubricate the upper v-rail. Do not use grease.
Lubrication Procedures:
Color change to Needle #1 or Needle #16 (press and hold 
, then press 
or 
).
Apply about two drops of sewing machine oil to a cotton swab and brush oil evenly on exposed (slanted) surface of the upper v-rail. Do not apply oil so heavily that it starts running off.
Color change all the way all the way to the other side (press and hold , then press or ).
Repeat step 2 for the other side; use the same swab without adding oil to it.
Color change back and forth a couple of times to move the oil evenly on the upper v-rail.
