mummdogg

The pits or air pockets in the primer vary with the grade and brand of primer as well as the way you mix it. They are caused by trapped air mixed into the filler.

The problem with spot putty or glazing putty is as you wipe it on with a putty knife or squeegee, a tiny bubble of air can get trapped in the pit and when you sand it down the pit can reappear.

Get a can of "filler primer" or "sandable primer".

Spray 2-3 coats to build up the surface. It tries fast so wait 5 minutes between coats.

When it is good and dry get a bucket of warm water and 400 or 600 wet/dry sandpaper. Keep the surface wet and dunk the sandpaper often.

Sand right down to the filler. The only primer left will be in the pits and scratches.

Repeat until the last coat of primer is smooth and free of pits and scratches without sanding through to the filler.

Put on a coat of "primer sealer" before final paint. It will keep the paint from soaking into the filler.