hi all . i'm new to the slot car game so bare with me . i've just purchased a couple of 2nd hand scx sets to set up for my grandson for his first slot car track . cars all work , controllers work and the track is in good to excellent condition. put her together and sorted out a few glitches and away we went . all good for the first few laps then both cars ground to a halt. reset everything , started again but same result. googled the problem and the topic of insufficient power supply kept coming up . so i purchased a new variable power supply, a powertech mp3800. variable voltage , 5 amp fixed . same problem . does a couple of laps then just stops . i'm buggered if i know what the problem is . thanks in advance.