The oil passage is a passage, not a pipe. To get around the obstructions at the top, I would remove the side cover and remove that 1/8" NPT plug and slide your safety wire down from there. Most people don't know that the passages are more accessible that way. The outside plug is at too much of a 90 degree to even get wire to move. Let us know if you are successful in getting a piece of safety wire down to the bottom in any case. I am betting when you do, the problem will go away.
