In addition to steer switches, there is a fuse for each drive motor. Also, make sure that your motor brushes are not seized up inside the motor brush block holder. This is common with the RC3000 due to the age of the truck. Also, the motor armature may need cleaning with a comm stone.
There are 2 switches on steering turntable that controls which drive motors operate depending on which way they are turned. Also 2 power fuses for l/s drive motor and r/s drive motor. Probably 175 Amp fuses. Could be as low as 140 Amp. If contactor pulls in then check fuses, contactor condition, cabling or motor itself. If the contactor does not pull in, check switches.