[Kidderman3]

I've owned a set of these headphones for about fifteen years and as they continue to provide great sound for recording applications I'm refurbishing them for continued use. With  replacement pads and a headband they look as good as new. However, one of the earpieces is pretty loose, i.e. it slides down the metal retaining rod very easily and appears to have lost the friction which it once had. The other side is fine. It can be adjusted to the desired height and will remain in place. I can see no obvious reason as to why one side has lost it's grip, i.e. nothing appears bent, out of place or broken. Whilst I can live with it, it's annoying to have to keep readjusting the headphones while I'm working. I'd be grateful if anyone could offer any advice as to whether this is something which could be fixed and, if so, how.

 

[GREQ]

You can very easily unscrew the circular panels on both sides where the cups attach to the headband.
Under there you can easily access the space inside.
If you can work out how to completely remove the headband (almost the entire headphone is modular) you can add a few layers of sticky tape to the hole the headband threads into.
Don't use a rough tape like duct tape or masking tape, as that will wear out after some time.
Smooth sticky tape allows smooth action and should last longer.
 
Then simply thread the headband back in after adding a couple of layers at a time until the friction level is high enough.
Then reassemble. 
 
This image may help.
http://www.canford.co.uk/Images/ItemImages/large/54-751_02.jpg