I am having problems with connections between fast track Joins . Some times my trains will run fine for hours but all of a sudden the train shuts off. I  have power probe test light with volt meter which I check track power rail for power some times its hot showing 18 volts and other times it has no power. The next piece of track will have power on center rail on both sections before and after Dead piece of track. I can also check for ground of out side rails. Some times it has no ground but like power rail will have no connection to next piece either side of that rail section. I have used electrical contact cleaner still having Problem. Its not the same area all the time. I have gone as far as putting jumper wire from rail section to another on back side of track which will fix that joint. Track is snap together as needed and fasten down  solid to table . but This loss of contact is driving me nuts . lay out is 6 x12 and i have 4 power hook ups around track to have no low voltage . Is there a fix for this or do I start putting jumpers on every joint.