Question: Suddenly with no previous deterioration after briefly stopping in "P", drive won't work. Reverse fine, slips slighlty in "L" a little more in "I" (engages with a real bang) and nothing in "D". Changed fluid and filter, checked selector and vacuum modulator. I would have expected some previous problems but their were none. Also, surely, in all positions the car starts in 1st gear so would move but then have change up problems. I accept that the 'box probably needs to be changed but before that would like to, at the least, try to understand the fault.

Answer: It does sound like the gearbox needs replacing, especially if it is slipping in L. Obviously you want to be certain that the gearbox is at fault rather than an external problem. You could always jack up the rear wheels and manually move the gear lever on the side of the gearbox into D – not the safest option but at least you will know that the gearbox has failed if the rear wheels don’t turn.Also you may need to check that the filter and the fluid have had a recent change and are at the correct level. Please let us know how you get on with this .

Question: Hi, what you suggest is the problem! When the rear is jacked up the wheels in "D" do turn. I appreciate that if it's slipping this can happen when there is no real load on the 'box but is there anything I can check before taking it out. Fluid and level is fine as per the book, I've taken the sump off and checked the selector, no issue there. I suppose that I'm clutching at straws but I hate being in the dark.

Answer: Hi, this does seem to point to the fact that the gearbox is at fault,reading what you have previously stated.