You have got a lot of good suggestions. If the track signal is that bad. I would start with the basics. Breaking down the layout into blocks and getting one block working with at least a 9 for a signal. Then move on to another one by reattaching the wires. The outside rail is important for a return path for the signal. I believe in connecting the rails with a jumper wire or alternating the outside rail in every other block. No insulating pins needed on the outside rails between blocks.
Not familiar with the Atlas pre wire rail joiners. I believe in 12 gauge wire from the TIU and at least 16 gauge going from the terminal strip to the track. I use Gargraves track. If I went Atlas. I’d solder feeder wires directly to the rails and probably solder smaller jumper wires from one rail to another. I do tend to overbuild things. My layout is fairly large and uses Buss wiring. Works just fine even though it’s not recommended. Every 3 ft. section is wired with feeders going to a buss wire. The layout is blocked.
Just how old is your Atlas track ? Is it a recent purchase or have you been buying it over the years and stockpiling it. The earlier track had a thick coating of blackening on the center rail that really effected the DCS signal. The recommended method was using a Scotchbrite pad to remove it.
