Is the following link a good representation of you handle assembly?
If you look under the handle blocks can you see a small hole into which an allen key might fit?
Thank you for that - you'll have to leave it with me until tomorrow when I can get the information. I have the same model downstairs in my kitchen but it uses the handles shown in the diagram I sent you. In that case the handle covers come off and you tighten the handles up using the screws behind the covers.