Thought I would use it on a walnut top this morning, and sharpened it like we did in school 50 years ago, got a nice burr on the blade, put the blade back in the scraper and got about 4 strokes out of it before it went dull. Tried sharpening a couple more times, and every time the burr goes bad in just a few strokes. Assuming I need a new blade. Anyone know where I can get a replacement? Or other remedy?