If it is a Cat Trax Brand set of beach wheels it is very easy.

1) Remove the cotter pin that is on the inside of the problem wheel.

2) Move the washer and the Delrin washer out of the way.

3) Inspect the Delrin rods (the bearings) and make sure all of them are present. I think it is 20 per wheel.

4) If all rods are present, then remove them and check for wear or degredation.

5) Using one of the existing rods determine the length and diameter of the rods. If you are missing one rod, pull out one of the rods to get the measurement. If I remember correctly they are 6" long and either 1/4" or 3/8" diameter. Don't trust me, jut use as a starting point.

6) Order the appropriate round bar (rod) from McMaster-Carr or MSC. You can access both online. Make sure you order Delrin so the material will be the same as the existing rods.

When you take it apart you will see how simple the bearing mechanism is. This is not a hard repair at all. I just bought a pair about 4 months ago and assembled them. It took about 15 minutes.

Let me know if you have any questions.