Also have Eskimo Mako 43. Hit dirty ice after about 6 or 8 holes & that did the blades in. Took my knife stone and polished them back up with good results. Have drilled at least 20 holes at Erie where the ice was 17-18". Still cutting fine the last time out, which by the way was my last time out for this season.
P.S. Doesn't take much "dirt" to dull your blades; also don't force the auger, too much pressure will take the edge off the blades. The weight of the auger should be enough to cut the ice if your blades are sharp.