Your motor looks pretty clean despite that old trick i learned long ago and some may disagree were all different was to flush it out with lighter fluid to loosen any sticky in there.
With all these twin motor setups when applying power off track the motors should start running nearly at the same time
Once running properly they are some great pullers i can attest along with the old postwar Trainmasters F3s and GG1s twin motors of the time.
