countax c800 mower hand break?

Before I pull the gearbox to pieces can any one tell me what the hand brake arrangement is inside the hydrostatic gear box on this mower. The hand brake has never been that good from new and now does not work at all. All the linkages are free and the lever on the gearbox moves a small amount, not seized. If I put a spanner on the lever and pull it as far as it will go as if the break was fully on the wheels still turn freely. thanks