Step 5: We remove the float. There is a small pin at the top of the float which can be taken out by hand.

The heat separated the two halves of each side of the float, so it had to be re-soldered. I used plumber's solder, which I assume uses an acid core. This was just a guess, but I imagine it will work OK. To check the seal, I weighed the float on a precision scale and got a weight of 17.9 grams. Next, I held the float under water for a few hours, took it out and dried if off. If the float had a leak, it would have been slightly heavier. Fortunately, it still weighted 17.9 grams, and I concluded that it was OK.