The blue steam loco 03 1022 of the premuim startup package 29845 has running gear lights. To light flickerfree, Maerklin had spent a capicator to the circuit board (drawn purple). Therefore the decoder has malfunctions. The running gear lights went off while driving or the smoke unit doesn´t work. After removing the capacitors, it works well, but the four LEDs are flickering, because there are connected to ground. It is possible to buy this circuit board as spare part for 25 DM 60 28 01 and it fits also in other staem locos like the 03 or 41. The spare parts comes without capacitor and it is still flickering.
It is quite easy to make the LEDs flickerfree. First I cut the circut to the ground (blue arrow). After that I soldered the orange wire from the decoder to the soldering pad of the not existing capicator (orange arrow). This modification is already drawn in the graphic.
Older steam locos, like the 003 131-0 (3795), are not prepeared for installing running gear lights. It is not possible to fix the circuit board with a srew. So it is not neccessary to cut the circuit to the ground point. Instaed I soldered the orange wire to this point (orange arrow). Additional a piece of the plastic part must be shortened (green arrow), because it is too high to fit the circuit board. I fixed the circuit board with glue. At last I soldered the brown-green wire from the f2 function to the board (purple arrow).