Nissan Patrol 4x4 (Africa)

Ok you have all read about my recent misfortune in Polokwane - well I am posting some pics of what came out of my engine. The control unit packed up, (no reason) two sets of gears got stripped (also not sure why or when this happened). I am told that work has previously been done in the same place, and that the engine has been opened at least twice before. Does anyone have any ideas what could have caused the gears to go - did it all happen at the same time or what?? Bearing in mind that I never heard anything funny coming from the engine bay.
On the bottom right is some of the white bath silicone that was found inside!

My gears also shot, but fat worse than yours. Also full of silicone.
Damage to my gears done by the bolts that hold the oil pump in place working themselves loose. 2 eventually fell out and landed in the timing chain causing a lot of further damage.
Who did your repairs?