This may be a dumb question, but figured I would ask before blowing up my Air. I seem to have lost my plug tip the connects the brick into the wall recently. I still have the extended cord, so she can still be powered up. Question is, is there any capability issues with using the plug tip from a 60W or 85 W MagSafe adapter from an older Powerbook if it fits into the brick and is considered the same 2.5A 125V adapter...Thanks in advance for any help!