part 87578 、89509、89668 and bb491

[yongxu wang]

Are you sure that you have only one library on your machine? maybe you updated a library but your editor uses another?
Otherwise, the part is avalable here http://www.ldraw.org/library/official/parts/89509.dat but you should not need to download a single official part if your library was healthy and properly configured.

Thank u, and one more question. I reinstall  LDraw today. But why does mlcad always remind me to lose a lot of parts?  

I have solved the above problem  thank you.