Right now im running stock emaxx tranny with alum input and alum output shaft,I do have supermaxx idlers, but im gonna put them in when i change to gmaxx single,after i do, it will be bullet proof, HOPEFULLY...
The press pins in the input shaft gears have been known to fail on occasion(usually after upgrading the rest of the drivetrain). There are a few ways to fix it, as mentioned in this post already. I usually replace the pin with a heavier pin and forget about it. I have never broken the pin twice(upgraded pins last and last). The stock Traxxas pins are pretty thin, actually. They weaken and break after a bit of high power running.
Well i broke my shaft pin today. I found that using a 2mm hex works well if you cut it with a dremel. Its a little hard to press in but it feels like it wont break or come out either.