I dunno.(Pardon my slang)
I myself had only limited success with Van de Graff. But as I was reading the
manual, it talked about cleaning the surface of the dome and the belt as well
as one can to remove oil and grease that builds up over a period of time. There
was mention of using a hair dryer as well. There was no mention of this in the
list. So I thought I would mention it. I haven't tried it since. If you tried
this process, please let us know if it worked.