I had the same problem. It's pretty brittle plastic. I broke mine off trying to replace it and the "rubber" grommet in the valve cover was plasticky. I also replaced the "rubber" hose attached to the valve (also very hard plastic) with some fuel line I bought from the parts store because I broke the new PCV valve trying to put the original hose back on. You may want to do the same.

Thanks,
Kris