With all those types of machine we categorise it as charger, battery, blockage/service or 'other'.
'Other' usually being something inside the main unit. With a Dyson you supply a motor body unit. In the case of Vax, parts supply is so awkward (from a supply and identification perspective), and the product so poor generally, anything regarded as 'other' is usually written off. We regard Vax machines as disposable - or a consumable if you like.
The problem is, if it may be the battery, do you want to buy one in in case it isnt? Not unless you are sure you'll sell it later.