Thanks for the input. Yes, the embroidery worked fine, but had a full bobbin and didn't use it up.
I have cleaned the area thoroughly. I am using the bobbins that came with the machine, so hopefully they are the right ones.
Spoke to the dealer and it seems to them that I am doing everything right and that the sensor is turned on. So, when I go for embroidery class at the beginning of next month, they will check it out.