It’s a bit daft, but I have not had much luck in googling results for this task. In getting my kart put together, I found that my rear caliper was leaking. Fine, let’s tear it apart. What I found is that the old o-rings failed and I needed to replace them. I did manage to find one place that had them in stock, and ordered enough for the full caliper.
They arrived today, and I have not figured out how to stretch them to get past the first part of the piston (these pistons have a groove cut into them for the seal to seat upon). It looks like I need a flat screwdriver and to do some ‘tire’ action, but I figured I would post here to see if anyone had any input before I might ruin a ring or two.