I know this is an old thread but did you sort out the problem? I'm having the same issue. can anyone help? How do you check if it is grounded properly?
What I would personally do is to remove both clusters, take them inside, get some fine sandpaper and clean the connection to ALL the bulbs, change ALL the bulbs, put back on the car.
Still blowing?
Check the below thread on a nice forum member that was so kind as to make pictures on exactly which wire to check for poor earth.