I have seen several videos of people trying to fix the conductance of the inner track current guides on 12V Lego trains using more or less destructive methods such as grinding the chrome from the guides. This is NOT a good idea and it is not necessary either. My initial solution was to run a small cart in front of the locomotive under which a small sponge was fixed whetted with alcohol. This worked most of the times. The principle at work is that the whetted guide improves conductance and prevents sparking.
Yet having a cart in front of my locomotive would prevent me from videoing the train as in the original configuration. I needed an invisible solution. I thought that regular model trains could suffer from the same problem, i.e. poor conductance, and although here too many brushing and cleaning methods can be found on YouTube, eventually I found the ATF solution.
ATF is short for Automatic Transmission Fluid. It is used in automatic gearboxes of cars. I figured that the principle preventing regular model trains from running would be similar to the problem faced by 12V Lego trains. So I paid a visit to my local Volvo garage and returned with about 10cc of free ATF. Since I wasn’t sure this was going to work, I built a small circular track to test. Then I used a cotton stick – the ones you can clean your ears with – and rubbed a tiny bit of ATF on the 4 circular pick-up contacts of the motor. And… it works brilliantly!