Update - i am fortunate in that I have another USB printer so I can plug that in and W7 then sets up a second USB port.
Then I can unplug the printer (USB002 stays)
Then I can go to Printer-Printer Properties - Advanced and select another printer driver.
Of course it dosn't help because that USB port is pointing at the printer I just unplugged and trying to print a test pages causes windows explorer to crash!!.
So I removed the device (USB002 still there) checked it had gone in proint management (it hadn't) so I deleted it there and at that point USB002 disappeared as well! Dont see its much use as it is connected to somewhere other than the printer connected to USB001
So it is beginning to look as if W7 will not allow two USB ports connected to the same printer.
If I add a printer (e.g. lasetjet 6MP postscript) and connect it to USB001 (currently connected to LJ6P ) which seems more logical, it all works fine but the the 6P printer disappears and is replaced by 6MP postscript so I do not have both printers visible.
It seems I need to connect two USB ports to hte same printer and W7 wont let me do that.