Jan Pijpelink
Minister of Fire
All materials, including steel expand when getting hot. Start with the cleaning, then lubricate again. If all fails you can always bypass the stove damper using a pipe damper. Try not to modify stove if not necessary.Baffle doesn’t look cracked from what I can see. Maybe it does just need a good cleaning like u said but it doesn’t explain why the damper is hard to operate when stove is running hot. That would lead me to believe the puck is warped.