my brothers car,hdi 120,000 bought damaged, 51 plate,went fishing, on the way home, snapped a follower, got home on three pots, sorted it out,went for a test drive,5mins later, limped home, with another snapped follower, WTF ?
excess wear on cam followers or camshaft lobes?
hydraulic lifter(s) faulty or not being charged?
Did you get all the bits of the first broken one out?
When you replace this one,disable the fuel pump so it won't start then spin it over on the starter till the oil light goes out, check that all the followers are still in place.