Well one possibility it to partially fill the slot--leave a little depth so some oil can get forward. You don't need a lot I think, just a little. You could always put a few drops of air-tool oil (it's pretty thin) down the venturi, and hang the plane nose down to get the oil to flow towards the bearing. When you put the oil in, you don't really need the crankshaft hole lined up with the venturi, since you want the oll to move forward, not backwards towards the backplate..