Yamada FZ 53 rebuild story and first run

This Yamada (Futaba in US) FZ 53 4 stroke RC engine was bought on eBay over 2 years ago.
It was sold in "pre owned" condition. When the back cover of an engine was opened, I've got quite a negative surprise. Former owner of an engine, as far as I understand from the internal signs (I'm not a Sherlock Holmes :-) yet), was make a kind of main bearing replacement, but he was not able to install a new main bearing exactly into the place. He decide, I think, to reduce the bearing height by grinding it on a sand stone or else. That could be the key reason of an engine sudden death. One of the balls (or part of the bearing separator) from the bearing was escaped and appears inside the case, in between of rotating crankshaft and case walls. This ball or part of separator was immediately milled inside into metal powder, with with immediate result - engine was jammed. I think, that this story could be very much close to the truth. Of course, engine was rebuilt practically from scratch, it takes a lot of time to complete the engine with all necessary spare parts. So, right now it is just a few seconds of firstly running engine. The whole story will be available few day's later, I'm currently working on editing.
Thank you for watching !