Blender from Warehouse

I got a blender as a Christmas present that had been purchased from the Warehouse and much to my disappointment it appeared to have a part missing when I opened it. No sign of a manual I eventually rang the manufacturers help line, no joy I would need to go to the retailer. i didn't have a receipt so going to the retailer was always going to tricky, however I thought I'd give it a go anyway. The Warehouse took a look at it and couldn't work it out either and fortunately they agreed to replace it.

Months later in putting the new one back together after washing it, I find it appears to have a part missing. However the difference this time is I know it doesn't as it has worked well for months. Further investigation shows that one part can easily be put in upside down, and at that point if you don't know better, it looks like a part is missing. Now a manual might have prevented this, I do sometimes read them as a last resort. However, I now suspect I got a replacement for a part that actually worked perfectly well although neither the retailer or the customer could work out how to construct it first tie around.  

I'm left thinking the manufacture could have put some instructions in the box, or at least on the internet. I wonder if they get a few of these returned and will eventually conclude assembly instructions should be included.