Sawing 1/2" hemlock shingles

For some reason the top ratchet that tips block in and out keeps missing a tooth when sawing 1/2" shingles, dont know if it's the pawl/gog or ratchet, but on 3/8" cedar with different ratchets it works fine. Then hemlock is can be measurable to saw at times, dont if it'sgoing to fall apart or be solid..