john hamilton wrote:


We have have tried 'WD-40', but that seems effective for only a very short
time.

cringe

That could be the cause of your problems. Firstly WD40 isn't really a
lubricant and secondly it can attack some plastics which can lead to
plastic hinges gettign stiffer as the WD-40 glues the faces together.
It's a bit of a lottery depending on the plastic used in the hinges.

You would be better off using either silicon grease or a dry lubricant.
Avoid anythign containing graphite because it conducts electricity and
shouldn't be used on electrical or electronic items. Farnell sell a dry
lubricant which should be better for this application:

http://uk.farnell.com/jsp/displayPro...MP=e-2072-0000
1000