That's pretty warm for the middle of the tank. You have to remember that the temperature of the tank isn't going to remain consistent throughout the year unless you have a thermostat. 8 months ago was winter time, and depending on where you live, the temperature of your house can fluctuate greatly even with the AC on. If he wants to get out, then that's even more of a reason to think he's not comfortable with the temps.
I would lower the temp of your tank first. Impaction isn't always the reason geckos stop eating. Soaking your gecko will probably stress the heck out of him, so it might be an unnecessary call for action.
But if it's what you're going to do, just get one of those Glad plastic tupperware containers, punch in enough airholes (I put in four holes that are big enough for them to stick their nose through), put in some paper towels and enough warm water to reach his belly. Then put on the lid and put the container half on the warm side and half on the cooler side. He'll probably stay on the cool side, but the warm side is to keep the water warm.
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Lovin' would be easy if your colors were like my dreams...