This is actually a lot of what I have been thinking. The fact that the songs I am messing with are familiar, does not mean that I have listened to them enough to know structure and lyrics. I can usually pretty easily play the various parts and sing the parts I know but the whole complete thing, not so much.
The obvious thing would be for me to listen to the dang songs a lot, right???
Thar's whar works for me, anyway.