If you can get some space between the dash and the shaft, you might be able to use a very thin soldering iron to heat up the shaft enough that it might loosen the glue? (But...Id really steer clear of the dash for fear of melting it). You could also use a lt spray of solvent, but, be sure to mask and protect everything around it for fear of taking off paint. As a last resort Id use a dremel tool on the knob, (not the shaft or threads), ...but only if I had another knob to replace it with. Have you tried tapping into it lightly with a rubber mallet? Perhaps a tap into it, then pull back on it, back and forth motion?
