There are two balancing pockets on each crank disk that are supposed to be full of lead. The cover plates are being removed to inspect for loss of lead during the shop fire way back in 1972. There appears to be dribbles of lead, but the first plate removed revealed a full pocket. Better to check this now, while the crank is out (and going to get new crank-pins and main shaft), not after a trial run indicating severe imbalance!

Photo by Rick Brigger