Lincoln rear disc brakes

Get a C-clamp and place the worn pad onto the piston, then use the c-clamp to compress the piston by tightening making sure you are in the dead center of the brake pad over the piston.

This is to protect the piston from damage or cracking, also to ensure that it is pressed back in with even force over its entire surface area. If you try any other method you risk damaging the caliper piston