Hi
As far as I know, MCC didn't print a specific manual for that vehicle , rather, they published a generic book that covered all of the military models in 1940. I do have a photocopy of it that Rory did for me years ago.
I suggest you contact Rory Ballard in Hampshire for help. I believe they are poured bearings and they are very expensive to have them rebuilt by a specialist .
Also Rolf from Norway who used to post here , had quite a lot of NOS parts for those motors. Don't know what became of the parts or him
Mike