T4 doing 360s

by Rich
(NY)

I have a IntheSwim branded version of T4 with two drive motors. Unit will work fine until in tries to change direction then it just spins in place in circles (one set of brushes going in one direction and the the other set in the opposite direction). I can make it go straight by pressing and holding the forward/reverse button on the remote. When released it goes back the 360s. Any suggestions. Thanks