The biggest help I have found is in the prep.
Hot soaking in a good degreaser for much longer than you think necessary. For some reason it seems to take longer to degrease zinc die-cast than other substrates.
Then a slow electrocleaning at low current. I have 5 X 20 gallon tanks running in parallel at 20 amps. Most of the parts soak a few days.
Then I have found a short dip in an ultrasonic tank filled with deagreaser results in bright and shiny bare metal for the new plate to bond to. The ultrasonic tank is pricey but it sure beats brushing by hand.
Then active and plate as normal.
It might seem excessive but it seems to work for me
David Farning