Your idea is a good one. Clean, oil, and see how it goes. If the pawl is merely dirty, oil and use will gradually free it up more. If the spring is weak... it won't get any better, but at least you'll know you need to replace the spring. You have already taken the hub apart and put it back together, so you'll know how to dismantle and do what you have to if the time comes. Looks like a fun and challenging project - it's really satisfying to get a 80-90 year old bike back on the road.