Rear hatch glass / washer not pumping

[saldip]

Hello all,
REAR HATCH GLASS / WASHER NOT PUMPING
Hoping someone has experience with this issue, or can shed some light on possible fixes.
I recently had to replace the rear hatch glass on my E70 – three weeks after taking delivery.
The glass installation was undertaken by a large and reputable national company in Melbourne, Australia, who have been very helpful in after sales support.
The problem is that the water pump supplying the rear wiper has not worked since their installation of the rear glass – and they don’t seem to be able to identify the problem.
The jet and feed are not obstructed, as a manual feed will get water on the glass.
The pump is not making that ‘pumping sound’ when I activate the steering wheel stalk.
Front screen pump and wipers are all fine.
Does anyone have a suggestion?
The auto-glass installer is most willing to have a third look at it, but they don’t seem to have a solution.
Could it be a minor connection they have overlooked?
Any thoughts are greatly appreciated.
X5 - E70 - Built MAR 2008
Cheers, Sal

was E53 petrol - recently upgraded to E70 Diesel