Dead spots in Atlas Switches

Hello Im new to the forum new to O gauge.  My father was into O gauge and recently passed away so I inherited his layout.  I have everything hooked up and am working out the bugs out.  His whole layout was MTH running the DCS system.  The track is Atlas with Atlas switches.  Have been checking all the track voltage and continuity through out the layout.  I noticed that at the Atlas switches I was loosing continuity so I soldered jumpers where I thought they needed to go and it has helped with the dead areas except for one switch.  If I run the MTH diesel that he had it gets through that area with no problem and at a low voltage of about 7-8 volts.  If I run his MTH Steam Engine through that section at around 8-9 volts the engine completely stops in that section.  If I run it at 11-12 volts it goes through that section with a slight pause.  Ive cleaned the engine pickups and lubed them.  I also have cleaned the track.  These switches are probably at least 10 years old.