They are easy to take apart and give a good clean. only 5 or 6 small allen bolts.
You will then be able to check if the spring is still springy or not, if not you can get a service kit for about fifteen quid i think that includes a new spring.
The only thing am not sure about is what type of lube to use!
I just used PTFE spray, about 3quid from toolstation, on my baileys dv and seems ok for now.
Anybody got any ideas what would be any better?