3rd gear linkage or synchro?

[Littleboy]

Hi all. Newbie here.
Have a problem with my doblo van. The 3rd gear keeps popping out. That’s why I joined this forum. Thought I’d get some advice before splashing out on a new gearbox.

 

[ceecff]

Welcome,
if it's 3rd only it's not linkage, should be 3rd synchro or cube.