Nothing. If you’re hearing an audible click and it isn’t oscillating, there’s an issue with the motor. If it’s In guarantee the Dyson team should repair it free of charge.

Your son might be able to return/exchange it. 

Hi, @JBarnes 

If you have assembled your machine correctly, but doesn’t oscillate, you would have to have it inspected. There’s a high possibility that it has a defect on the “Oscillation Motor Assembly."

Visit Dyson.com and contact them via Whatsapp or call the Dyson Helpline, and I’m sure they would provide an appropriate assistance.

Thank you for taking the time the answer. We werent sure if we had assembled it wrong (although it was very straightforward) I think it must have a fault.

@JBarnes 

I do agree. Assembling them is very straightforward and it seems to me that you need to get it repaired. As you’ve mentioned that you just purchased the product recently, there’s a high possibility that they would just provide you with an exchange.

Just call or send Whatsapp to Dyson and I’m sure they would assist you further.