Thanks Matt, I tend to rock the fsc back and forth, but that sounds like a reasonably good way to o do it.
I did a test patch earlier for this gum job on the tarmac.
Gotta be honest I'm not too optimistic. I couldn't find a temperature and flow rate that I was happy with. It either blew the tarmac, slightly damged the area around the gum or it wasn't strong enough to remove the gum. Mind you thinking about it I didn't adjust the pressure valve, I didn't see the point at the time.