Found my mistake.
# append the new_id (the index for the document) to the list of ids to consider
# new_ids_to_consider.append(new_id) # wrong one
ids_to_consider_l.append(new_id) # correct one
I used the wrong list to append.
Needed to read the directions a little closer next time. DOH!
Also, commenting out that remove line is a mistake.
When I put it back in and rebuilt the hash tables, and reran the whole, I submitted it for grading and got 110/110.