Well, the GE repairman showed up and said he'd never seen anything quite like it before ! His best guess was that the factory had managed to pair an old design set of runners with a new design set of wheels, and they weren't quite compatible :-( The solution he came up with was to replace the wheels with ones from an old style repair kit, but mounted onto the new style clip-on fixings. Total time about 15 minutes.

It is now working fine, but the repairman left wondering how he could make the folks back at GE understand that it had happened ! My guess is that design will blame the factory and vice versa !

Jim