I had a seize front bearing on my new TT91 4 st. I was only running at 9600 rpm when it happened. On closer inspection, I think the prop driver managed to lock the bearing's shield. I took the engine apart and found bits of metal from a few disintegrated ball bearings (front bearing). Is there supposed to be a spacer /washer between the front bearing and prop driver to prevent direct contact of the prop drive and bearing shield?

On another observation, I found the cam gears and the geared crankshaft rather dry. How is this part lubricated? There are no holes allowing lubricant to flow onto the cam gears. The rear bearing is sealed both sides as well. Shall I replace the rear bearing with unshielded ones so lub oil can flow through and reach the cam gears?

Thanks.

Regards
Daniel