So I bought a Dyson DC14 All Floors last night. I put it together this afternoon after reading the directions, then turned it on and started to vacuum in my living room. We have old Berber carpet and a smallish (5x8) area rug (because the Berber is so rough and stained).

The vacuum did just fine on the carpet setting on the actual carpet, but as soon as I started vacuuming the rug, it made this horrendous screeching noise. I turned it off the carpet setting and onto the bare floors setting and the noise stopped, but I could.not.push the vacuum forward at all (that's some powerful suction!). I vacuumed the rug with the carpet setting pulling it backward with no noise, but if I tried to push it forward...oh my, the screeching!

The thing that has me confused is that I had absolutely no problems vacuuming the small doormat (maybe 2x3).

Do I have a dud or am I doing something wrong?