Hi, wondered if anyone might know what this might be: occasionally my gearstick makes a pinging noise when I shift gear, usually from 2nd to 3rd but sometimes from 1st to 2nd. When it does, the gearbox becomes (and stays) really loose through neutral, which can make it hard to find 3rd especially. It's like there's suddenly a massive hole in the centre of the gearbox and I'm guessing where to push the gearstick to get 3rd.

Doesn't happen all the time so before I take it in to be looked at only to be told it's all okay, has anyone heard of anything like this before?

TIA

edit: forgot to say, this is a MK2.5 Ford Focus (2008 '08 facelift)