I tried to replace my first cracked rib today. I've read the Elliott and Stelmok and Thurlow books and studied the threads on this site. I picked a cracked rib towards the middle that had been repaired once before. It appears that it was glued to the planks, some of which were new and others rotten. I tried grinding the ribs from the inside with a grinder and a Dremel with a cutting wheel, and then tried to drive the rest of the tack down with a hammer and nail set. That worked on many tacks but some were so solidly dug in that the hammer and nail set didn't budge them. Some of the tacks had somehow curved back without emerging on the inside of the canoe. I also tried working them out from the outside by trying to pry under the head of the tack from the outside. Finally, the repaired rib seems to have been glued in place. I don't think it was just varnish seeping in from the edges. I also tried drilling the tacks from the outside. I ended up tearing up the planking, some of it reasonably new. I need to replace 4 other ribs and the last two can't ribs at each end. Any other suggestions how to get tacks out and remove ribs?