Possible Clues:

• Bethlehem Sparrows Point was one
• It's got three metal feet and scales
• Weighing-machine with unequal arms
• It's hard, difficult for Cockney to find balance
• Three metal feet could give one balance
• Weighing machine exposed crooked deal with tyres
• Top performer applied to director about elusive weighing machine
• Jacking up cart with earth in allows one to take the weight
• Weighing machine somewhere next to foundry?
• This'll show you how heavy three iron feet may be