sometimes loose power when crawlin up CC M Max

[toy4crawlin]

Help please
Just got my new Super running about 7 LBS

most of the time I cannot crawl up slow, power cuts out

Mamba Max, not warm, makes squeak noise, crawler starts rolling back down
BM16 brushless

NEW 8 cell Sub C battery

axial tranny 81 spur 19pin also tried 87 / 23-way to high

1/8 scale ring/pinion 13/43 3.3:1

Do I change setting in ESC ? or is my gearing to high and what should it be?

finding gears to fit axial is not easy, need to find correct setting or right Spur to buy 2 Spurs that will provide good results

I cannot fit 81 spur 18 pin, maybe a 82 /18 or 83 18

thanks