Windshield Knob

[V12Bill]

I am trying to remove the windshield know that opens the windshield in my 39 Ford pickup.I have removed the set screw and loaded it up with PBBlaster but have not been able to lift the knob from the shaft. I don't want to add heat for fear of melting the pot metal. I need to check the regulator and get it working properly, but first must remove the knob. Any hints on this project? TIA

 

[V12Bill]

Got the knob off. The base of the knob hidden from view under the upper panel of the dash, has a 1/32" groove in it. The edge of the upper panel was caught in that groove and prevented the removdal of the knob.