Thanks for your response 180, hatch it is, ( tailgate or boot door here in UK. Two countries separated by a common language?). Not sure if the problem is a damaged lock mechanism or fractured vac line. Only had the car one week, door opened during my inspection but hasn't worked since. Air pump works AOK as do all other locks. Past experience tells me that small dia. poly pipe is a good substitute for yellow Merc tube. Any spray shop supply will have stock at little cost. I will post outcome once temp rises above freezing.