Need help with stuck Air flow dial.

Okay so story behind this is I was climbing a steep hill, and my truck got overheated. Not way past the red but it was nearly at it. At the time I didn't know my radiator had a very small crack it so it keep leaking all the coolant. So maybe a couple days after that I was changing where the air flows (at your feet, out the dash, on the windshield ect.) And so now it doesn't move, it will turn maybe a centimeter but it wont switch. Do you think a nearly overheated engine could cause the plastic to melt? Obviously plastic would melt but its pathetic if your engine overheats this happens. Is it a lost cause? AKA bring it to a shop, and have them look at it?

Sorry its an essay but I really could use some help. Winter is on its way and I need to defrost my window. (Considering I have to scrape the inside of it sometimes)

Thank you!

 

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