My husband wasn't home and I don't have a key to his garage workshop to get in there and sniff out some white grease so I used the next best thing...Vaseline. Using the end of the screwdriver I covered the offending area with the Vaseline and worked the buttonhole lever to and fro. In no time at all it seemed to loosen up. I put the cover back on and replaced the screws. Needless to say, I'm not sorry I did. The buttonholer works wonderfully!
This is absolutely the best fitting blouse pattern ever. It is my TNT pattern. I'm going to experiment with interchanging the sleeve from other patterns. Why try to fix what isn't broken?