I recently replaced the weak mangent on my old (but otherwise perfect) 'Lyme Regis'. The motor pulled like, well, a train, but a bizarre problem ensued: the new magnet is so strong that it lifts the trailing bogie clean off the tracks! Short of bodging with gaffer tape and carboard I couldn't think of a way round this. I gave up and put the old magnet back on. Any suggestions? And any views on the damage done to these ring-shaped magnets by removing from motor frame?