My Philco 116-122 has started random popping. Bad tube? Dirty socket?

I just had that on my newly acquired Dewald. It ended-up being the band switch. I heavily sprayed it many times with CRC and so far it seems to be fine. De-oxit would be even better. In the past when I had similar issues, the first thing I would do is take the chassis out, clean and lube everything and scuff-up grid cap connections. 9 out of 10 times the set would play fine after that.

My Philco was repaired and now is in regular service. It's everything I hoped it would be and more.