I'm getting ready to fix the window regulators from my 71 charger. I ordered the replacement sliders for the ones broken/missing from mine, but I'm not entirely certain how to go about replacing them. I was expecting new plastic to snap into place but the new ones actually incorporate the metal ball which they are install into the regulator arm. I'm wondering the proper way to remove the old one/install the new ones. It looks like the original ones are pressed into place but I don't want to assume and wind up mangling the regulator in the process. Anyone out there have some insight into this?