There are two ways to fix a Z-axis homing error on a BambuLab A1, this is the hard way.

Printed on an OpenCentauri with a 0.2mm nozzle. Filament used Sunlu PA6-CF, it only needs 0.4 grams, and won't take long.

It has to be strong and heat resistant. It will be subject to continued high temperatures, and occasional high forces. The PA6, or other material will anneal in place, ensuring a good fit. PLA may melt in place, making a mess, don't use PLA or other low temperature filament.

Install as per the photo, its should be a tight fit, use pliers or a hammer to get it into the right place. Remove the support after fitting. If you put it in backwards it will not discombobulate successfully.