How do I replace this Malta shoe?

Thanks for reaching out to us. The shoe shown here reminds me of the 15-159. To replace this small white shoe on the string, you would need one standard plier and one locking plier. With the standard pliers, pull down the string about a foot and lock it in place with the locking pliers. Now, you can change the shoe. When completed, install the shoe, hold the string with the standard pliers, release the locking pliers, and gently release the string, so as not to break the shoe. I hope this helps.