earlwb,
As you know I'm a bit of a troublemaker in that I ask, and I hope I get, folks to think. This is exactly the kind of thinking I hope to instill, both in the readership and I hope for me. I really enjoy it when somebody can teach this old dog new tricks.

Now to be clear I didn't say that the tubing didn't solve some problem I just don't think the mechanism credited to solving the problem was correct. But the fact that you saw bubble without the tube and none with the tubing does led credence that you did seal something if nothing other than allowing control of the clearance to allow some oil to pool in the valley to make a seal. I can't subscribe to that as the flow would be away towards the discharge port and not allow replenishment of the valleys with oil.

I too think that the single leaf spring detent, or holder, that puts a side load on the needle is a very poor design.

All the best,

Konrad