Thanks, guys! That's notably different advice than I'd gotten previously -- namely, that I probably didn't need to clean my pans throughout a season, given the small size of my operation. But if you're cleaning every boil to every few hundred gallons, then I'm well overdue. No wonder I have so much buildup! I just picked up a bunch of vinegar and will be cleaning them out tonight. Credit to the wisdom of my sugaring elders!