Traditional AEG's are not happy with spamming in semi. If you really did 36k rounds, erm i think you are doing extremely well.
I wouldn't expect stronger uprated gears to last anywhere near that long in semi.
I sold my NGRS because they all seem to be a pain in the ass to keep running, have more expensive and often hard to find parts. Compared to a normal AEG, they are also much harder to work on.
My NGRS was an M4 model, but nether the less. It shit the bed and ripped the back of an upgraded piston off after probably 12000 rounds.