[Shop-talk] Removing Symmons diverter valve?

[Jim Franklin]

In preparation for renting my house I'm putting $2 in for every $1 I'll see. One of these projects is to replace the diverter valve so tenants can take baths. Well not only won't the valve turn, but it won't pull out. Before I drill it out and ruin the body, are there any chemicals known to dissolve whatever is holding the valve in there?

It's this one:

https://image.riverbendhome.com/Base/54535.jpg

and I've already torn off the first 1/4" using a lag bolt. I tried heating it a bit but the fiberglass enclosure started smoking. 

thanks,
jim