Buy off the shelf rebuilds. ( And I can / have fixed or rebuilt _everything_ on a car from engine to rebuilding window motors to rekeying locks. )

When the pistons start to stick, it is from rust build up between the piston and caliper top lip. Any marks on the piston won't seal. Rebuilders grind then re hard chrome the pistons.

The dust boots are difficult to install without a press and a tool to hold then square. The dust boots have a steel ring inside the rubber that will tear out if you hammer on them.