The hose is the main part that pushes down, because of how stif it is and the way it's bent it pushes on the head

So long as the old one isn't broken you can twist it till it fit pushes the heal of the sole plate. I find this problem on a lot of dysons, generally when they are cold, once the hose has warmed up it seems to work ok

Thanks for this guys. I had the same problem so my husband took the hose off and turned it around (mine is a Dyson DC14 all floors) and it did the trick. Dont know how long it will last but if it does it again I will know to buy a new hose.

Thank you EVERYONE. I have had this same problem for a VERY long time. I just flipped the hose today and tada!!! MY dyson is back too! It appears that the hose acts somewhat like a spring to keep the vacuum head down on the carpet. THANK YOU!!!

I too have a DC07 that has an issue where the soleplate doesn't automatically align on the floor.
However, this is not due to the internal hose. It is due to friction between the pivots of the brushbar housing and the lugs of the cleaner head.

This 12 year old DC07 just got a brand new chassis, cleaner head and clutch. When reassembled I noticed that the brushbar housing does pivot ,but is stiff. If I push the heel of the soleplate down it stays.

I disassembled enough to reattach the brushbar to the original cleaner head and find it has no friction at all. The lugs (holes) appear to be the same size.

I don't know what is causing this?