When I was working on the bike t'other day I removed the sump plate to check for shrapnel. There was nothing nasty in the sump or screen. Also, only about a 1/4 pint of oil was in there, so I'm thinking that the ball check valve, (that I recently replaced) is doing its job.
duTch, the B31 lash caps that I fitted to my A10 Inlet valves do not go right down onto the valve collets. You raised a concern about them.