I saw what i think was the W.E. model 233 many years ago. It was the civvy forerunner to the ARC-4, with the meter on the front panel. 

A friend had a BC-639 rec and when you adjusted the B+ to spec, it would smoke. ( Smoking is bad for you. ) But when you cranked down the B+ like 50 volts, it worked just fine.

A digression, but i was last night looking at a book on 'CB Linears'. There was a paragraph up front that explained the basics of the "smoke theory of electronics". A diverting  alternative to our usual concerns with electron flow.

-Hue Miller