Hello Kathleen,
Do you mean the actual tension or the complete unit ? if it is the unit when you open the faceplate you will see a screw level with the tension unit, if there is no screw the the unit is a complete screw in type which means you will have to turn the whole unit clockwise until it is tight and you should still be able to adjust the tension.
drivewithken@blueyonder.co.uk, June 2008
