Yeah, the phone needs to be reprogrammed. You need to get that MSL. If you have no other phone to call Sprint, I suggest going into a store. No other way in my experience to fix a error 67...
Edit : actually, I'm assuming you have internet access, so I'd go to
www.sprint.com/chat and explain what's going on. They will reprogram the phone with you. At that time write down the MSL for future use.