captainc, If you had not mentioned it, I would not have noticed that english was not your first language.

Regarding sanding, nobody likes to sand any more than they have to. Unfortunaltely you must sand everywhere you want paint/primer to stick. If you skimp on that vital part of the paint preparation process, the new paint will eventually peel and flake off in the areas where the sanding was inadequate. That is also true for primer that was allowed to dry past the time specified in the instructions on the primer container.