My WR400 has started leaking just a few drops of coolant in the area under the impeller cover. There is a hole in the case that the impeller cover attaches to, just below the impeller cover and just in towards the center of the motor. At first I thought that a screw had fallen out of that hole, but it doesn't seem to be threaded. It is possible that the coolant is coming out of that hole. Or I suppose it is possible that the seal under the impeller cover is leaking, so it just seems like the coolant is coming out of the nearby hole. Has anybody had that particular problem? Thanks in advance for any comments.