-MIKE- writes:

From the manual...
"3. Note: Some units may have small holes inthe attachments and/or
pins on the spindle shoulder. These are not used or required for this
model."

Mine (model 67256) says on Page 8

2. Place attachment over Spindle (5) shoulder facinf
forward. Line up the holes on the attachment with the tabs on the
Spindle shoulder (See Figure A).

3. Attachmentsa may be mounted at angles up to 90 degrees left or
right. The attachment should not turn on the spindle. If it can
turn, make sure that the holes on the attachment line up with the
tabs on the spindle and tighten the cap screw securely.