Also you need to be reasonable, if you have a giant layout and 100 locomotives, but only 1 or 2 have signal issues, you may be better off looking at the locomotives themselves to see if you can add some metal and get better field coupling back to the Earth ground.
Touchups with ground wires work well (at the cost of being ugly).
Also one big thing is for the GRJ booster and legacy base itself is make sure they aren't plugged into a GFCI plug or power strip which has extra circuity in the ground for circuit interruption that 455 KHz doesn't like flowing through. We saw some super weird stuff with a few brands of power strip.
