Re: lower unit problems
reason I asked is...it's normal for water to drain from that hole, also you might see a bit of unburned engine oil from the exhaust dripping there sometimes. I don't think a leaky gearcase would drip there, but I'm not real sure.
there's two slotted screws in the lower unit, starboard side near the forward (boat) end, one below the gearcase "bullet" the other above. They're the only slotted screws there. Take out the lower one (the plug) then take out the upper (vent). The plug has a magnet, it'll normally collect a small about of tiny metal shavings. Observe the oil as it drains, look for metal fragments or splinters...also the oil turns black with use, but if it looks milky at all that means you got some water intrusion. That's how you know if it's leaking gearcase oil.
Not sure about the quantity but a quart will be more than enough, look for "outboard gearcase oil" or something to that effect, walmart or most sporting goods stores have it. They also sell a plastic pump, less than $10, that fits the quart bottle, with a threaded tube that screws into the plug opening. Can't be sure it fits your 1955 model though, hope it does. Pump new oil in until it comes out the vent hole. Replace vent screw, then replace plug. if the pump don't work with yours, you'll have to just jam the bottle up in there and squeeze it in.
