Hi
Do you have a photo of the grip and the attempted fitting of the black rubber cover into it? I don't have the K-1 or grip, but I do have the K-3II, K-3, K-5 and Samsung GX-10 (K10D clone) all with grips, and I've always found fitting the little rubber cover to require careful alignment and a good push. I don't doubt what you're reporting, but I do find it hard to believe something this fundamental would be missed by Ricoh - so, with respect, I have to consider that user error might be the problem
Are you sure you're aligning the cover properly in the space provided? Again, a photo would help