Sorry it has taken me so long to report back...I just had the chance to do some work on this. I replaced the motor to esc bullets that came with the combo pack with some 4mm Tekin bullets. That seems to have fixed the issue - I just ran it hard on the road and front yard in the rain and had no issues at all.

In looking at the old bullets - they are the swivel kind...not sure why you'd make them like that. And there was some corrosion on them but I'm guessing its the swivel that was causing it.

Thanks for all the help! So as of now - I'm assuming it's fixed.