[Chimera-users] how to connect broken ribbon

Hi there, Sometime, when I use chimera to make a ribbon presentation of protein, the helix region will either broken or does not present properly. Similar thing can be happened in Pymol. But, Pymol provides a command called "alter". When I rebuilt it after altering, broken helix can be repaired. I'm wondering is there similar function in Chimera, or is there a suitable method which can be used to deal with it. Thanks Best regards Pu Qian