welling yxb-250-4 induction motor spin start direction is inconsistent
The motor requires a capacitor for starting. One of the red or yellow wires is connected directly to 120V, the other is connected in series with a capacitor to 120V. Judging from the capacitor value, I expect that the capacitor is for starting only. It must be disconnected when the motor gets to full speed. Note where Cap: 50uF is marked on the label. If you have been doing that and have failed to mention it, the capacitor is probably bad or the connecting and disconnecting mechanism is bad.

A 50uF PSC cap seems to be typical for a 2 or 3 Hp motor. It is possible that this 1/3 Hp motor is a PSC (permanently-connected, split-phase capacitor) motor with a 50uF cap, but it seems quite unlikely. Since the motor is specified for use only in a clothes washer it seems likely that the connect/disconnect method is a timer or current sensor in the washer.

However, it also seems likely that the motor will start consistently without a load in the selected direction with about any value of PSC run-type capacitor that may be tried. It is probably ok to try about any value, but don't run the motor with a continuous total current higher than the 3.5 amps marked on the nameplate. The motor may start under load or may not depending on the capacitor value and the load's starting torque requirement.