CL9 - 2nd gear pops out

[vaynah]

In last few weeks my 2nd gear started popping out.
Happens when I'm in high revs and get off the throttle, and once happened when going over speed bump.

Car needs gearbox oil change as it's leaking, so I'm hoping that's the problem.
However I am aware it's a possible synchro issue?

 

[Gerryf]

Don't go wasting your money on an oil change......sadly it's repair time or a replacement box.