"Throw the bubble away cause it sucks. Go to the craft store (I went to acmoore) and they have clear , 2 piece xmas balls for .68 "
The bubble hasn't been a problem with mine,but finessing the interior and chassis has,not to mention one of the many paint schemes the car had over it's life span. I did pick-up another one at a show that was cast a little better.You're build has inspired me to look it over again and see if my skills have improved over the years to fix what was bothering me.