@Tregrill  The Dyson DC40 internal hose can be located here with part number 924796-02: https://www.dyson.com/support/journey/spare-details.924796-02 . At this time, it is out of stock, so we do recommend signing up to be notified once restocked. 

Thanks for replying but I don’t think you have fully read my post !

“I  have bought a genuine part from Dyson and it doesn’t quite fit at the handle end, it seems to sit a little high. I have tried pressing very hard but it gets no lower. Am I just weak or could it be faulty?”

@Tregrill We can’t determine if the internal hose is faulty without confirming if the right sku was purchased. There is a high chance that the wrong sku was ordered. If it is the right part, it is best to have the hose replaced at a Dyson Service Center. 

It was bought on line from Dyson UK with this part number. 924796-02

Its the correct part from what I see. 

Maybe you have a model that isn’t listed? Have you tried looking for a part by entering the Dyson serial number?

Use Support | Customer Service | Contact Us | Dyson to enter the serial. 

If your Dyson is listed, maybe its a faulty part. You’d need to reorder a new one and return the one you have!