I read this story once about glaziers in the 80s. They had to move huge sheets of glass with just these basic suction cups and pure muscle. The article said a crew nearly lost a pane that weighed half a ton because a cup slipped. One guy said they all just stood there, holding their breath, waiting for the crash. Makes you appreciate a powered lift and proper vacuum handles.
In 1983, a friend who installed storefront windows told me about a time the suction cups failed on a windy day. Ever had a close call like that with old equipment?