Overlander,
Some older machines actually specify petroleum jelly ( Vaseline) as the lube for their motors. Others call for their factory supplied lube, Singer for instance.
In this case Singer has defected out on us and no longer sells the motor lube. As far as I have read the closest grease to use is petroleum jelly.
That is why I have mentioned it. Hopefully somewhere there is a grease that's more like the Singer grease than petroleum jelly.
Joe