Spectrum F7A and B

[Rusty Rail]

Good day to all. I have recently purchased non DCC Spectrum HO F7A and F7B units at a local show. They are new in unopened boxes and are DC only. I have purchased a sound decoder and a function only decoder to install in the locomotives. It seems like a straight forward install, but I have been given some mixed advice. On the internet I have seen where you are required to snip off the wheel wiper and then solder a wire on the truck frame. Nowhere on the Soundtraxx web site does it instruct you to do this step. So my question is: should I snip the wiper off, or not? 
Any help gentlemen would be fine. I am also installing a sound decoder in a Bachmann GP 7 as well. Thanks to all who respond in helping with my dilemma. 

Rusty Rail

[Len]

It's not the wheel wiper that gets snipped, it's the upper chassis wiper that gets taken out. These are instructions for installing a decoder in the F9, which is similar:

http://www.tcsdcc.com/Customer_Content/Installation_Pictures/HO_Scale/Bachmann/EMD%20F9/EMD_F9.html

Note that the piece that rubs against the back of the wheels is NOT removed, only that piece that rubs against the bottom of the chassis.

Len