Bachmann S4 DCC/Sound Diesel Switcher starving for track power-

[Sunshine Express]

My Bachmann S4 Diesel Switcher is stopping and starting frequently on track power. I have tried to clean the pick ups with a fine brush and  methylated spirit ,but this only lasts  for a short  time,and then it stops. Tracks are cleaned frequently. I have never taken the body off,and would like the advice of our forum before i do anything further. I  have had high praise  for this  little switcher,as it has always performed well,working on my 10x5 Small Town US Layout.   Owen

[ALCO0001]

Hello,
I have a few of these issues with mine , and I fixed them myself,by first powering up the loco ,and lifting each truck up off the rail to check to see  witch truck is not picking up current from the rail.
If both trucks are picking up current ,you need to take a look at the brass pickup tabs behind each wheel to make sure there is no foreign matter  interfering with them ,they are thin and in my opinion a little to weak , you should remove the truck side frames , pry up gently on the center locking tabs with a small flat blade screw driver, remove the drve axles bu gently pulling them out wile holding the truck to not damage the truck mounting clips.
Next bend the tabs outward some to increase the spring tension they have to the back of the wheels,wile your there make sure the wire is not broken off the solder joint on all the pickups,if so they need to be re soldered.reinstall the axles if the wires are good carefully wile tucking the pickup tabs behind them kind of rolling the axles back in for proper gear mesh,do not force it or you might break a gear tooth!
Make sure you put the axles in the same way ,the gears are off set to one side ,if you put them in wrong the gear will not line up with anything but air and the side frame cover will not fit back on,been there!
Next ,test it on the rail to see if you problem still occurs,If not your done ,If it does , remove the shell by unscrewing the coupler pockets with a small phi lips screw driver,slide the coupler pockets out of the frame , remove the shell by grasping the tank and the hood and wiggle wile gently lifting the shell off evenly.
Next follow the pickup wires from the trucks to the circuit board plastic tabs ,check these well to be sure they are mot broken at the tab itself or look like they were pinched between the shell and the frame,if not remove the plastic tabs that hold the wire to the circuit board.
one at a time and check the wire is not broken inside the tab ,if so strip off a small amount of insulation and reinsert the wire in the hole the direction it was ,probably from the bottom and reinstall the tab/cap the same way ,if the wire is going into the board from the bottom the slot in the tab will be on the bottom.
IF after this you are still having problems, set cv 8 to 8 ,RETEST.
Finally ,if you do not feel comfortable doing this or none of this works ,send it to service,Hope this helps!
Jack

[Sunshine Express]

Thank you Alco000,for your very detailed advice.This is the  best of fellowship in our hobby. I can now approach the problem with confidence. Owen