Vax's water filter vac was called the WaterJet, and I think the model number was V-100 or something similar. It was fitted with a clear drum, and the motor unit looked very much like that of the old Philips 3-in-1 cleaners. It worked by bubbling the dirty water through a perforated screen in the bottom of the drum, so you can imagine how nice that would be to deal with on a daily basis. Didn't sell well, and went as quickly as it came.
The Vax Luna was a standard 3-in-1 type cleaner, functionally similar to what came before it but tarted up a bit to look more modern. By the time this came out Vax were really losing their grip on the market, and they were desperately trying to claw back sales.
The problem wasn't that their existing machine was dated, however. It survived the Luna by a long shot, and still sells today albeit with a few minor updates over the years. The real issue was that 3-in-1 machines were no longer in fashion. The market for them was getting a little saturated by now, and those who did have them rarely used them as their daily cleaner. More often than not they were just kept in the garage and only pulled out once or twice a year for shampooing jobs. As a result of this they rarely wore out, which kind of put the kibosh on repeat sales too. The big drop in demand did not go unnoticed, and before long we had relegated 3-in-1 cleaners to special order status, so as to make room for something else on the showroom floor.
The Luna was of a similar time frame to the Sahara bare floor cleaner, Wizard bagless dry canister, and the last of the Vax 3-in-1 uprights. All products that were supposed to reverse the company's fortunes, but didn't. Vax seemed to have a real problem at the time with actually making stuff people wanted, and were too slow to diversify, insisting on putting all their eggs into the one basket whose time had already come and gone. Had it not been for TTI coming along and taking over, I really don't think they would still be here now.