Henry and the vacuum cleaner

So my 19-month-old son LOVES the vacuum. Like seriously loves it. When we get it out, he runs around it, giggles, and pats it and says 'GENTLE! GENTLE!' basically he treats it so nicely that we were saying 'if we can convince him that babies and dogs are vacuums, he would do great with any baby!'
We have a Kirby vacuum. To put the hose on the vacuum, you have to take off the head of the vacuum. That is how Kirbys have ALWAYS been. My son FREAKS OUT and shouts OW!!! OW!!! and sobs whenever we put it on the vacuum. We have explained to him that it doesn't hurt the vacuum, etc. but it does NOT matter. Then as soon as the hose is off, he shouts 'BYE! BYE!' and runs to the closet where we keep the vacuum and hose. Once we put the hose back in the closet, he runs back over and pats the vacuum, with tears streaming down his face saying 'gentle... gentle' it is so bizarre and we can't help but laugh to ourselves even though he is SO sad.
Now here is where it gets really bizarre. It seems to be only this particular vacuum. When we vacuum at my mother-in-law's place, he is scared and cries. When we rented a carpet shampooer, he hated it. But our vacuum, even though it is very loud and heavy, he loves. I don't understand this at all.
And I fear that the day may come where we have to replace our vacuum and he will be just crushed :-p