[Chimera-users] command related to the alignment of the ribbon form and the ball & stick form

Dear All, If by Chimera we open a PDB and a corresponding mrc file, and we display the molecule by both ribbon format and ball & stick format, we can find there is a minor disalignment between the ribbon representation and the ball & stick representation. I remember I have read somewhere by a ribbon related command the Chimera can align the ribbon representation and ball & stick presentation nicely, but I have forgotten where I read the tutorial or introduction. Will you please tell me the command to have chimera to get good alignment of the ribbon representation and ball & stick presentation, or tell me the weblink of the corresponding tutorial or reference? I am looking forward to getting your reply. Smith