Carb cleaner / brake cleaner and lacquer thinner are way to thin to do the job as they will evaporate quickly.

Mineral spirits (oil base paint thinner / parts washing / stoddard solvent ) works fine however you will have to let it soak a while.

Check for brass / bronze parts in the trans, if it has any, do not use EP lube ( extreme pressure ) as the additives will attack the brass / bronze.