Tumble drier problem?

Zanussi WJD1667w washer/drier. On tumble drying cycle clothes are hot and steamy at end of drying cycle (not overloaded). The condenser is completely clear, the fan is working, the wiring to bottom sensor is in place and thermostat at front of chamber reads 2.5ohms.
Should I be able to hear/see water from cold inlet when on drying cycle? There is a clear plastic tube running across top back of machine - should I see anything in this when drying?