canon 400mm 5.6 repair help

[den]

Hi,i have the 400mm 5.6 that devolped a loose barrel ,this as never affected anything it just means when i use it i have to make sure i pull it in when holding.
When it started doing it i pust some heavy duty tape round it (hence the marks they will clean off when i get round to doing it) ,now today after a couple of years i have decided to take it off and have a look at it,its a lens i have not used for a while and while it was taped up it was fine
In the photo you can see were its loose ,the opposite side is fine its just this area in the pic ,to me its not worth sending in at the moment and i would be quite happy having a go at repairing it ,or sell it on cheap with it working but with a bit of a loose barrel... i have tightened evry visable screw ,does anyone have any idea what could be the issue ..Thanks
400mm 5.6 (1 of 1) by dennis greenwood, on Flickr

 

[Chipper]

No. Maybe ring Don Clark based in Wotton under Edge; he does repairs and I would imagine he would know what to do and whether, if you did decide to get it repaired professionally, it is cost effective.

 

[den]

Thanks

 

[den]

Just called them , although he can't tell me the fault but he believe the top internal screw needs tightening , a couple of hours labour , to be honest if I could find a tutorial on how to strip it down I would have a go myself