Auto is not the best way to charge NiMh imho. You have no control over the size if the NiMh peak the charger is looking for when set to auto, suspect you can't find out either with the minimal manual. Charger was prob looking for a 'smallish' voltage rise and triggered charge termination on what was really a false peak relative to being completely charged.

Auto only gave you this good of a charge because your pacs are new. It will do an increasingly poorer job as the pacs get older. Try a manual setting with peak sensitivity of 3-5mv/cell. When I was actively using these, I got good results with 3mv/c on new pacs and then bumped it up as the packs got some cycles thru them.

What you did thus time will obviously work as well, its just a pia and requires more time than being able to charge all the way thru...