I'm afraid that it was lack of lube too. I have purchased cables both ways, some with lube and some without. I always check and lube anyway, even if they come with some on them, just so I know it's done my way.
But it could go back to your speedo too. Is it rebuilt? If not, even if it was working, if it has old hardened grease in it it might have reached a resistance point and jammed, thereby kinking and breaking the cable. It's surprising how hard that grease can sometimes be.