I've been restoring a 1913 Old Town Charles River CS that someone covered with fiberglass and filled the gaps with something grey and hard. I removed all the exterior glass and interior varnish, but have not removed the filler between the planks. I'm replacing probably 1/3 to 1/2 of the planking, but the rest still has the filler in the gaps. Should I be digging it all out? Also curious about small gouges from removing tacks in the old planking, from the ribs I replaced, and whether I can get away with filling in the gouges with filler or should I (1) leave it alone or (2) replace that planking as well.