You have probably already read this, but using the Goof off with a firm fine brush instead of sanding with it. I find a firm toothbrush works well here. This "should" break up the glue into more manageable pieces to get it out of the wood. Once it starts to ball up, you can wipe with a rag to really get rid of it for good. To give you an idea of unknown glue spots give it a wipe down with gum turps or similar and you will see in good light the inconsistency where the glue spots are.