I replaced that oil pickup tube on my 353 because as near as I could tell it was leaking out around that tapered rubber part where it goes into the oil tank.
it fixed the problem for me. I just try not to bring it in out of the cold to a warm shop, and if I do I try to remember to crack the cap so it doesnt build up pressure in there and push oil out. not sure if that is making the difference or not. but my saw doesnt leak anymore