The speed button doesn’t stop from 0 to 5 it jumps to number 6

Dear Sir ,

my stand mixer has problem with the speed button .

model : 5KSM150PSEER

serial no : W61227092

it does not stay on number 0 it jumps to number 6 So in order to put it on and off I have to unplug the mixer .

would u please help me to see if I need spare part and how I can order it .

Regards

masoumeh

skinhair.desouza@gmail.com