Product review (1 stars): It was perfect fit, and the post now stayed centered and ...
I had also been having the problem of wheels coming off lately and finally lost one pin holding the wheel.  I came to this product page and saw posts by Katwoman and My kind's mom and did the same.  Hence, all credits go to them.

I purchased the following parts from Home Dept.
- Everbilt Aluminum Binding Posts 3/16 in x 1/2 in (Item#: 284 706) - $1.18 each
- Everbilt Stainless Flat Washers 1/4 in (Item: 246 799) - $1.18 for 6 washers

The diameter of the aluminum post is a bit smaller than the diameter of the hole.  It still worked OK, but I wanted it to be a little more solid. I needed some kind of spacer to fill in the space. I looked through and found one of the straws from my kids' old sippy cups fit through the hole perfectly. It was about 7mm in diameter.  I cut it into a 1/2 inch piece and push it into the hole.  It was perfect fit, and the post now stayed centered and stable.

I started having the issue with the wheels 2 years after I got the dishwasher, so even if you buy this assembly, you will have the same problem in a few years.  It is a design problem. I would recommended you do the same as what I did instead of getting this parts.