I'm not convinced that the clips are fully seated. I see that they are at the ends, but they could still be hanging up around the back. I suggest you press the blade of a screwdriver against the back part with the screwdriver parallel to the mainshaft and tap on the end of the screwdriver with a small hammer or mallet. The idea is not to force the clip into the groove, but to tap it back against the clutch shoe so it can pop in. Once it's properly seated, you should be able to put the point of a scribe into one of the holes of the clip and rotate it to make sure it's seated.