Product review (5 stars): My machine is a model number WTW6200SW2 and it works perfectly
The part I received was brand new / never used or opened and fit my machine perfectly, even though the lid lock part on the new one looks very different and is much larger than the old one (I think the new design is an improvement).  It's been over a month and I haven't had any more problems - it's working exactly as before.  I'm very happy with my purchase.
If you want to know how I fixed my washer, keep reading.

After a frustrating search, I finally figured that this part was the one I needed
Then I looked for a "how to" video and the one that I think helped me the most is called: "Whirlpool Washer Lid Lock Assembly Replacement #W10619844" on Youtube.  You can either enter all that in or just go to Google and enter "Nx6tJnyAi0Y" and the video should be the very first video that Google returns. (I'd just post the link but Amazon might consider that spamming.)

If I remember correctly, the tube was "threaded" just slightly differently on my machine than on the video, but it was really easy to figure out and everything still fit properly.

I would just like to add that very few places will accept returns on parts that don't fit unless the mistake is on their end (you ordered one part and they sent a different one).  So unless you are very confident that you (a) have the right part and (b) are capable (have necessary tools, etc) of fixing it yourself or (c) you're prepared to accept the consequences of a repair gone wrong, you might just want to call a repair technician to fix it for you.  It's not the cheapest option but it's usually costs less than a new appliance.
Anyway...
I rely heavily on reviews when deciding on a purchase, so I try to be helpful when writing mine.  If you did find this helpful, please give it a "thumbs up" so that I know I'm on the right track.  Thanks and good luck!!