Console script to find bad paperclip image uploads and fix them.

fix_images.rb

def head_status(u)
  uri = URI(u)
  Net::HTTP.start(uri.host, uri.port, :use_ssl => true) do |http|
    request = Net::HTTP::Head.new uri

    response = http.request request # Net::HTTPResponse object
    response.code
  end
end

UnitImage.all.select{|i| head_status(i.image.url('small')) == '403' }.each{|i| puts i }.map{|i| i.image.reprocess! }