I haven't a better Tip on how to handle than what has already been written by Pahoo. Nor have I tried the acetone & transmission fluid mix. But, I'd be careful with acetone use this time of year in a closed up home. Like Pahoo said Liquid Wrench or perhaps Kano Labs (Kroil) is the best way to proceed. Both are excellent creeping penetration oils. Which ever you choose is a win win for your project. Good Luck Sir.
Watch it!!! their both out to get us.