Insert the holding pin supplied with the BC1600 through the slot in the upper gear head.
Turn the blade nut counterclockwise, using a 1/2-inch wrench or an adjustable wrench to remove it.
Remove the lower washer, cutting blade and the upper washer. Keep the upper washer for use with the line-cutting head.
Remove the blade guard using a 5/16-inch wrench or an adjustable wrench. Keep the blade guard to one side for attaching the line-cutting head.
Turn the spool retainer beneath the line head clockwise and remove. Pull off the spool and line head from the trimmer.
Insert the holding pin supplied with the BC1600 through the slot in the upper gear head.
Turn the drive connector bolt clockwise using a 5/8-inch wrench or an adjustable wrench and remove it from the trimmer.
Slide off the upper flange washer and keep it aside for blade head installation.
Remove the screw holding the grass-cutting shield in place with a screwdriver. Remove the shield ready for blade installation.