I ordered a Singer Quantum years ago from HSN. It has never given me any problems. It was one of the first Quantums made. The stitches are perfect. I use this machine for all my machine applique, it sews perfect satin stitches. I can use any type of thread with no trouble. I don't know how the new Quantums are but mine is worth every penny I paid for it.
If the foot pedal is the air tube, buy clear tubing from a hardware store and slit it open lengthwise to slip over the foot control tube. I dropped a rotary cutter and it cut the tube. I had to buy a new foot control.