TOKYO—Japan’s factory activity grew at the slowest pace in eight months in September as output and orders contracted, while that of the services sector remained in its downturn, underscoring the protracted impact of the coronavirus pandemic. The au Jibun Bank Flash Japan Manufacturing Purchasing Managers’ Index (PMI) slipped to a seasonally adjusted 51.2 in September from a final 52.7 in the previous month, marking the slowest growth since January. Factory activity has faced headwinds from disruptions of parts supplies due to the rapid spread of the highly contagious Delta variant as well as a global semiconductor chip shortage. The September data showed Japanese manufacturers’ output shrank at the fastest pace in a year, while overall new orders contracted at the quickest speed in 10 months. The au Jibun Bank Flash Services PMI index remained in contraction, though it rose to a seasonally adjusted 47.4 from the previous month’s final of …