This modification is simular to the one I did with the 26-3134B. The difference is simply that this time, I did the modification better since it has been integrated inside the original RF box.

So I first unsolder the original modulator box and remove most of the component in it. Then, slowly, re-using the same holes as before, I reconstitute the circuit taken from the 6847 book. You need to be careful in what you solder where to make sure traces are linking where you need. It's like making a new smaller puzzle with parts by re-arrange them differently!

The re-arranged circuit lookes like that.

Once back on the board it looks like almost original once the cover plate was placed back (not shown on the next picture but you certainly figured it). To see the schematic and datasheets of 6847 and MC1472, see the modification I did with the 26-3134B board.