The trick is to install the boot on the piston with the lip hanging off the bottom of the piston. Now the tricky part is to gently place the piston in the opening where it goes while working the lip into the groove all the way around. When your sure you’ve got it in the groove, push down on the piston making sure it is squared in the hole. At this point I usually use the handle of a hammer to push the piston on down. It is a PIA till you’ve done it a few times.
