The first time I changed the oil filter I didn't have these problems. I think it's because I reused all the old O-rings except for the large one on the cap. I think that's how the book said to do it.

This time I replaced all of them (well, 4. I didn't know about the one under the cap). The large one is correctly installed in the 2nd groove now. But I can't get it to seat. The O-ring is compressed into the housing OK, but it won't go much further than that. The cap becomes very hard to turn by hand and I don't want to break it.