Get some new chutes and a good staple gun. Possibly a hardhat to keep from sticking your head with roofing nails,A few wide boards that span at least 2 ceiling joists so you can lay on them and a LOT of patience.

Yank out the cracked ones and try restapling the loose ones. The fiberglass will decompress after you get off of it. It ain"t a fun job I've done it in 2 houses now. Ended up with a few nail sticks in my head. First time I did i was in my late 20's Didn't bother me much then, except the fact it was a low pitched hip roof. Did it again last year at a different house, and i'm in my late forty's, bothered me a lot that time. Takes a lot of flexability to do it. It's a big pain in the a-s job but it needs to be done.

Don't try straddling ceiling rafters. Just asking for more work (foot through ceiling)