Installing the VGS1 is not too easy on the 480. I did it some 5
years ago when I bought my 480 and remember contending with a
bundle of delicate wires and some small screws that needed to be
removed then replaced after installing the chip. The small
screws hold a cover over the VGS1 chip and maybe the spot for the
other filter. Installing the same voice chip was much easier on
the Ts590. 73, Jim WA6EKS