I had a DC15 in for a refurb and repair the other week. The changeover valve had snapped, requiring manual activation of the changeover unit, far from ideal!
Luckily, it is an easy fix.
To start, strip the machine down to the state below
The assembly comes as below
The parts feel alot stronger than the originals
To replace it, you need to remove the lower hose
Then undo the screw in the yolk spigot
and remove the yolk spigot
Remove the static cover next
The owner needed it back before the parts came as he was moving house, so I refitted the bit that needed to be there, and he carried on manually reclining the machine. Before, this was a mess of springs. Basically, strip it all out as below...
Recline the machine and lay it on its side. Remove the broken bit. The wheel assembly will go floppy once you remove it
Take the new spring mount assembly and insert it into the hole (it only goes in one way)
Fit the long spring to the locating stubhttps://manchestervacs.co.uk/DysonForum/Themes/default/images/bbc/img.gif
Fit one half of the spring attached to the moving cover to the assembly
Fit the other half of the spring to the machine
Fit both sides of the moving cover to the spring/cover mounts
Fit the covers, as the screw that goes through it prevents the big spring from coming off and ensures the movement is kept smooth.
Test and marvel at the now working reclining mechanism!