The water pump shaft has a constant side load due to the shape of the impeller bore in the casting. That load wears the cylindrical bore in the bronze bushing into an oblong shape, which means the shaft isn't centered as it goes through the two rubber oil seals.
The symptoms are that water drips out of the weep holes between the two seals, especially when the engine is running. (If there were no weep holes it would mean that the water would proceed through the second seal into the crankcase area and mix with the oil.
The pump can be rebuilt for about $15 worth of parts: two oil seals and a bronze bushing.
This is the old bushing, still in the casting and well worn oblong.
This is the casting, cleaned up and ready for new bushings and seals.
The bronze bushing is 0.875" O.D., 0.625" I.D., and 1.250" long. The part number I used is "B1014-10 BGW" but anything with the above dimensions will work. It and the seals are easily obtainable at Bearing Specialties, Kaman Bearings, and any similar bearing suppliers in the USA and elsewhere. These are common parts...there is nothing "marine- rated" about these parts.
The bushing can be pressed into the casting using an arbor press, or by pressing it between the jaws of a large vise (using an appropriate size of wrench socket as the press tool,) or by the use of a hammer and socket. Because of shape distortion during pressing, the bore may be tight for the shaft and thereby require reaming back to the actual 0.625" diameter. I used an adjustable 5/8" reamer to widen the bore appropriately. A machine shop can do likewise, or you could attempt to find a bushing with a slightly undersize O.D. to make pressing easier which might lessen any shape distortion.
The oil seals are 1.124" O.D. and 0.625" I.D. Depth doesn't matter provided there is space between the two seals to allow water to drip out the weep holes. The part number I used is "C/R 6229" which is a double-lip seal (each seal has two sealing lips.) It's actually one mil undersize for the bore (which makes it easier to press into the bore.)
Press the inner seal all the way into the bore (metal side inward toward the impeller,) then press the outer seal into the bore (metal side outward away from the impeller) so that its metal surface is flush with the casting. Lubricate both seals, then carefully push the shaft into the bushing and through the seals, rotating it as you go so as not to injure the rubber seal surfaces.
Install the impeller and C-clip (although the C-clip may actually be unnecessary.) It's probably worth adding a drop or two of oil into the impeller cavity to keep it lubricated when the pump first rotates after it's reinstalled on the engine.
Shaft extends through the rear oil seal.
Front cover shined up and installed. Stuff works better when it's clean!