Zz will be set by the two dials at the top. Each one is 1 slot in from SS. I am at the hospital right now so I don't know what the letter combo is but I think it is BL and AK is SS. The 401a manual is the same for 401g. The width lever determines how wide so 1 is narrow 5 is wide. Your stitch length lever will determine how many stitches per inch. If the stitches are not right you may have it off the proper letters. It could be slightly out of zz time and may need to be serviced. Also if the stitch selector knobs aren't moving freely it would need to be serviced. You may need to check the tensions settings.
The 401g is not very common here but 401a machines are everywhere.
Did you know you could put that machine on a treadle? There are channels in the back for the treadle belt. Somewhere on QB there is a thread about it. You may want to search Singer 401g in the search above right.
Last edited by miriam; 06-18-2016 at 12:02 PM.