This was previously discussed in an archived email but I can't find it right now. Does the setting connect_mode=0 use the CONECT records in the PDB file or not? I think it does. Apparently in pdb code 1ABE, the CONECT records were changed in a 2005 revision. Two alternate sugar conformations are now interconnected when using the current 1ABE. The old 1ABE (from 1993) seems fine.
Should setting connect_mode to 0 before loading PDB fix it? I don't think it does.