How do I change the drive roll or wire inlet guide on the Miller Matic 211?

To replace the wire inlet guide, press on the barbed area or cut off one end near the housing and pull it out. Push the new guide into the hole from the rear until it snaps in place. For the drive roll, locate the open slot and push the drive roll completely over the retaining pin, then rotate it 1/4 turn to the closed slot. The drive roll has two different sized grooves (.024 and .030/.035) marked on the end surface.