Nilfisk Grey-Line IVB5 M and the Nilfisk-ALTO Attix 5 wet and dry commercial vacuum cleaner front castor wheel, it's secured by an Allen screw, which can easily become loose and give the machine an irregular gait, giving the impression the wheel is faulty, when really it only needs the castor fixing screw tightening up.
It's no longer available, and the replacement part number is 107409103 but it doesn't seem correct, it's far too big so use Pn. 29714 whilst they are still available.
As it's light, maximise the saving on postage and buy some of the related parts below, such as dustbags and the filters or a new floor tool.
At the moment standard postage within Australia, is capped at a maximum of $20!