[Transmission] 1.6 HDI 90hp 2007 Mysterious gearbox

[Osiris777]

Hi, I've read all the gearbox related threads but none of them seem similar to the issues I'm having. Long story short:

The gearbox is temperamental. 1st and 3rd gears are sometimes hard to select. It's completely random. 

What's done so far:

- 1 gear linkage changed as the old one cracked 
- new clutch
- new gearbox oil

There is no play on any of the gearbox linkages, there is s little play on the plastic ball joint but nothing serious. The car has only 68k on the clock.

What worries me is the play on the gear selector, in my opinion it comes from the gearbox. Links are fine. I've recorded videos so you can see what the play looks like:

https://youtube.com/shorts/jZXcfIo5l14?feature=share

https://youtube.com/shorts/eOGh97_hCyA?feature=share

Has anyone ever had similar issues? It's hard to believe the gearbox died after less than 70k miles...

One more thing: sometimes when changing gears (any) I can hear a knock from somewhere around the engine, it doesn't sound bad there is no grind etc there is just a single knock.

Thanks in advance for any advice!