The original prop was a plastic x432, the motors are geared 1:1. The speed control was a servo-operated mechanical switch which changed from parallel to series wiring on the two battery packs. These were hugely popular when introduced and they went through several generations before the original maker went out of business. In the late 1980s MRP proudly touted the Miss Bud as "the fastest RTR in the world" - at 25 mph.
ERROR 604 - Caller's Buffer Is Too Small
1. Ensure that your port is not configured to a low speed
2. If you are still having problems, contact your counselor