NEW DELHI : An acute shortage of workers has turned the roar of machines to a soft hum at a footwear factory near New Delhi, just one of thousands in India struggling to restart after an exodus of migrant workers during the virus lockdown.India is slowly emerging from strict containment measures imposed in late March as leaders look to revive the battered economy, but manufacturers don't have enough workers to man the machinery.The big cities -- once an attractive destination for workers from poor, rural regions -- have been hit by reverse migration as millions of labourers flee back to their far-flung home villages, some uncertain if they will ever return."Sixty percent of our labourers have gone back.