Classic/Antique Car Repair: how do I remove stuck mechanical water temperature bulb from engine?, penetrant, intake manifold

Question
Hi;This is my first visit to your site.
I need to remove the water temperature bulb from the intake manifold of my 53 Chrysler. I have undone the nut that holds it secure, but when I try to pull it from the brass well it will not budge. It is mechanical, so I don't want to cut it. I sprayed some penetrant into the well but no luck so far. If I cut it off, Can I just silver solder it back together? Thanks for any insight offered.

Answer
Dave;
 Hi  I do not understand, can it not be unscrewed ? I do not think it is just sitting in there it has to be screwde or pressed in, have you tried to take the entire unit out> I do not think you will be able to solder the cast iron. it could be pressed in or taped , I would clean it up real good and loof for threads. , be carefull ok