Garden chippers are notorious for being time saps for repairers. The light to medium duty machines are generally not very well engineered and users frequently fail to respect the limitations of the equipment they have. When you add in the fact they are often infrequently used and then infrequently maintained it makes for a perfect storm of trouble.
It looks like that engine both didn’t get regular oil changes and was run with insufficient oil. Those older brigs engines stood up to years of use if given regular maintenance and treated with some mechanical sympathy.
