Hi, I have 3 dco7 he-pa vacs , one works very well and you can tell that its suction on the carpet is far better than the other two . One of the other two recently had a 1600w pattern motor fitted , all three have had new filters and have been emptied out . The switchover (brush to wand) valve units and springs look to be working OK . the bottom hoses are OK and i have checked the vacuum readings at severall points on each vac ie cyclone exit port , cyclone inlet port , end of wand , and at the brush head end of the short flexi pipe . All seem to be similar (6.5 ins hg ) . I have tried swapping the cyclone unit from the good one to the other two in turn (no improvement).
The vacuum measurements only prove that each motor is capable of pulling the same ultimate vacuum as each other , but of course cannot measure the actual flow rate . One thing that i noticed was that when the good example was in its upright position and then the handle pulled rearwards, the visible part of the sole plate at the front of the vac came up and its heel came down . in the two poorer examples , this movement was not apparent at all , so after a clean & lube of the pivots, the movement was a little bit better , so i helped it along with an elastic band slipped around the flexi hose in its middle and also around the u bend , thinking that the sole plate has to move readily to adjust to the floor angle . Result = barley perceptible improvement . I wonder if these replacement pattern motors are as good as the original Dyson units , or have i Missed something fundamental ?.