wwbroe:
I have gone through this before. When I sent in my GPS for repair to Garmin they send you an exchange unit thy do not fix the one you sent in. The new unit of course has a different ID number than your old unit.
Therefore now you have to re-unlock your mapsets before you send them to your 60CSX.
The reason they all still work in Mapsource is because they were installed with a workable unlock key.
Unfortunatly it a key workable with your old GPS and not your new GPS. Mapsource just accepts any workable key.
I hope this sets you on the right track. Some of the tutorials and links above clarify the different unlock
methods. Good luck with your new GPS.