Needlebar.org says this:
Late 19th/20th Century New Home Machines
The vast majority of New Home machines have the serial number on a
Slide Plate.
Earlier models are often referred to by the "class" name eg New National, which became the model U, then US.
After the Free Sewing Machine Company took over New Home some models were sold under both the New Home and Free names (as well as other badged names). New Home machines started to use letters in front of their serial numbers in about 1930. The letters represent the model type. This applied to all models, including those with a
Badged Name.
"New Home" models include: AC, AD, DA, DNHM, JL, KK, LN, M, MS, NH, NHR, NHL, NLR, TS, U, US, NLB.
Free produced models with the following designations (note duplications): A, AD, AAE, AE, ALE, ALR, AN, ANR, ARE, C, CCE, CE, DARE, FH, G, GE, K, KE, L, LE, N, NE, NMO, M, MM, ME, MO, P, PE, W, XE, ALB. For further information about Free Sewing Machine models, see the
NeedleBar Picture Library.
Demise of New Home, National & Free
Needle information is taken from Mr NeedleBar's Needle Book compiled by Chrys Gunther, in which additional interchangeable needle makes and information about these models will be found. In many cases a 15x1 (2020) needle may be used in place of 20x1 and set slightly down.
I'm not sure if it's implying that I can use a 15x1 needle or not?