On my recent vacation in England I picked up a Graham Farish Class 37 locomotive to add some British character to my otherwise North American layout. Only problem is this locomotive constantly derails over one of my turnouts. When I examined the locomotive I noticed the wheels have nearly 1mm of side to side play in them. None of my Kato, Atlas or Inter Mountain locomotives have this much play. Is this normal for Graham Farish locomotives? I suspect that what's happening is the wheels are not all perfectly in line and as a result they're catching and causing the derailment. Any suggestions on a remedy??