True, but Mama said it was a toy.
I know this is posted over and over again, but I would never give a child a toy machine. They will never grow up wanting to sew. Find a SInger 99 and convert to HC. Now while off that podium...
There are only 2 machines, per se, that take the W& G machine needles WGx64. The W&G and copies/clones of it made by other manufacturers and the Original Express. The Original Express actually takes WGx63 which does not have the groove all the way, but it accepts the WGx64. On the other hand the W&G will not take the WGx63.
I trust the Toy list, but I think it would be best to see a pic.
I checked the ISMACS interchangeable needle list and Stitch Mistress only comes up with the 15x1 and the name only comes up once.
Genero Stitch Mistress [Toy] 15x1 J Y 16 Y AA D 62 10 Y J 705 Sy2020 These are the different designations for the needles for this machine, depending upon the manufacturer. The first and last are what is important now.
It is possible the mechanic did not get the needle all the way up, there is a broken shank in the way or something else.