The 1-2 accumulator bore in the GM TH350 and TH350C cases can become worn or scored from repeated oscillation during normal operation. This can result in delayed engagements and 1-2 slip from low line pressure, which could cause intermediate clutch failure. Once the bore is damaged the case must be thrown away. Sonnax 1-2 accumulator sleeve kit 35719-01K restores hydraulic integrity and saves worn cases.