I had that problem, when I first cut the shaft on my new paddle, i think I got half a paddle full of water.
Couldnt wait for the hair dryer...........so i blasted it with the heat gun on hot.......got the handle out in no time at all......
Tipped a lot of water out, shoved the still hot handle in and bobs your uncle............
i have a KE NALU paddle






Dont try this with yours.......and if you do damage the paddle buy a ke nalu, its idiot proof.......I should know

Best of luck