[Radioroslyn]

I would suspect that the thumb wheel next to the tuning that operates the bandswitch also switches it from manual to push button. Manual would be with the pointer at it's lowest position. This is a guess as I've never had a 40-195 but it does seem a resemble the 41-300 which have. From the schematic the chassis are all most the same from the IF back thru the audio output stage. The mix/osc are different as it use two XXL tube (7A4) triode. That makes a low noise front end.

https://philcoradio.com/gallery2/1941a/#Model_41-300X