Offroad-Express

Has anyone had anything like this before. Replaced batteries and this started happening. Starter winds over flat out but won't crank engine on first turn of key, makes a good clunk when key is released and starter slows down (noise possibly due to engagement with ring gear). On second attempt at starting fires up straight away.
Pulled starter out pinion looks ok for 220,000kms.
Checked pinion throw out on battery pack on garage floor. OK.
Greased pinion shaft.
I've heard there's a throw out clutch rebuild kit for these.

Any advice appreciated.

Definitely has to be the clutch unit in the starter. Go see your local auto electrician and get a new clutch. New unit may or not come with the bearings, so get new bearings and may have to use your starters pinion gear

Just called auto sparkies new clutch kit on the way.