Okay. Maybe I'm a bit thick when it comes to extension rods, the instructions are a bit too small for my eyes but in a nutshell the problems I'm having are -
It only partially opens (the last two segments).
The sliding lock, it does nothing when you turn it. The partially extended pole just comes hurtling back down to Earth, It's not safe for an Osmo.

Any ideas anyone?  
PS I managed to open it, really stiff - now how to lock while extended?

You grip the handle and twist the entire rod (holding the head) counter clock wise all the way to unlock the extension rod. Twist it clockwise to lock.

This tutorial video from DJI will probably help too

Hello!
Here, it's the tutorial video about how to install and use Osmo extension rod for your reference:
You can also download the PDF format of extension rod guideline at http://dl.djicdn.com/downloads/o ... _Start_Guide_en.pdf

If you have any doubt about the quality of your extension rod, please contact your dealer firstly for help.

Hi guys
Thank you both. The PDF guide is much better to see than the leaflet that came with the rod.
I had seen the first video featuring Ty but it was all over too quick and I didn't get what I was doing wrong. However, this second video is much better and actually states turning each rod segment (0:44)  to lock them in place. I thought the wrist straps upper fixture (0:28) had something to do with the locking of the rod, silly me! Cheers

I ordered an extension, but it only has 3 sections and is about 2.5', but in the videos and the pdf it show a longer stick.

huh?

@innovativethink is one of the sections still stuck inside? 2 of mine were and unfortunately required brute force to get them out.

Spud Posted at 2016-3-19 14:21
@innovativethink is one of the sections still stuck inside? 2 of mine were and unfortunately require ...

hard to tell, I've puller pretty hard and nothing happens, and it doesn't look like there is enough room for more.

update: okay, your were correct, brute force was required!

innovativethink Posted at 2016-3-25 16:37
hard to tell, I've puller pretty hard and nothing happens, and it doesn't look like there is enough ...

When I got mine some weeks ago, I opened it up to its full length -- and then found that I couldn't get it closed again. I emailed dji about it, before I realized that you have to use a bit more brute strength then you think would be necessary. Whether it loosens up with use, we will have to see.