Hello Joan,
Bottom runners I think you mean the teeth, make sure the needle plate is on correctly to begin with, once you have checked that lift the presser foot turn the balance wheel so the teeth are at the highest point and make sure they come above the needle plate, if they don't then you need to take the botom off the machine and you will see an adjusting screw to raise the teeth, if the teeth are above the needle plate and it is not feeding the material then it will be a shop adjustment.
drivewithken
September 2010