A833 questions

1) The O-ring on the reverse lever has to be the best you got, cuz the oil level is higher than the ring, so if it doesn't seal, you got a leaker and worse is that you get to take it apart again.
2) the front Retainer has to be a tight fit into the BH, in order to keep everything concentric.
3) the yellowing of the brass rings does not seem to affect how they work.