Auto Gearbox selector now smooth with no click between gears

Hi all - I am in the UK and have a 1993 Hiace camper (ex Japan) 4wd with an auto gearbox and 2.8D engine. Everything works fine on the gearbox but the gear selection is now smooth between 1st, 2nd Drive & Neutral. I am guessing there is some kind of knurled bush or similar to "click" between gears but am struggling to find a diagram or part. It was working perfectly a couple of days ago when camping and failed on our return. Can anyone offer some advice etc? Thanks in advance.

I think the indent is inside the gearbox - possibly a spring has broken.
But look under the selector to be sure!
- else you'll need to speak to a gearbox specialist, A1 gearboxes in St. Neots is good (last time I went anyway!

BTW your gearbox will be common to some other more popular Toyota 4WD of the same era - those forums have more expertise on this area.

Great - thanks for your advice.