Hi
@superocd,
I have always considered Kirby's Shampooer to be a flawed design.
I've considered this thoroughly and dismissed the whole concept. So too their Head Massager, Handi-Butler, Sander, Jig-Saw, Drill... These attachments helped to sell the vacuums. Clinching the deal. Persuading unconvinced customers. Kirby wanted to offer more than competitors.
When all Filters, 'O'-Ring seals, and Strips are new and perfect, you still have moist sudsy foam around the Brushroll, Brushroll bearings, Belt, Driveshaft, Lifter, Housing, Fan, Emptor, (and to a lesser-degree) past your Motor.
The Brushroll works the wet foam into the carpet. It's not 100% efficient. Suds have to be flying off the rear of the roller and into your machine.
When you vacuum up the dried soap (with encapsulated dirt) some of that is going to be moist. So you have wet, sticky, clinging, clumpy debris inside your Vacuuming head (or Nozzle & Hose), Fan, Housing, Emptor, and Bag. Some of that air passes by your electronics and Motor. It's asking for trouble. At the very least, you'll have some corrosion, every time you use it.
Shake 'n' Vac was considered by some engineers to be the culprit for many rotting hoses and corroded/clogged vacuums. And that's a lot drier than Kirby's watery foam.
So why don't we hear of these machines blowing-up and failing when the Shampooer is used? They tend to be used only a few times, when the machines are new. They underperform at carpet washing. Thirty years after they were bought, they'll usually still have half-a-bottle of original shampoo. Many are never used at all. And corrosion is evident in almost all Kirbys.
I would never allow the Kirby Shampoo System anywhere near my machines. They're for dry dust and dirt only. It's risky enough picking up paperclips and Lego bricks. I throw away all the Shampoo Systems and Handi-Butler attachments when I get a machine.
Kirby is for vacuuming.
VAX is for carpet washing.
The wife does the massaging.
Black & Decker does everything else.