Bumblebees...
My Philco 48-1001 had a ga-zillion of them. I replaced them all, of course, along with all the Electrolytics AND the 7 or 8 Micas. Also, I replaced all the CandiOhm Wirewounds. It sprang immediately to full life after that. Just minor tweaking to optimize it's performance. Thank God, as it is a very complex chassis. I would have hated to troubleshoot or align the set.
Result? One of my best performing 10BP4 based TV Sets. Great Picture, mediocre sound. The Tuner is a weak spot of the design, as it wanders a bit, and you have to occasionally tweak the Tuning Oscillator. But the Video performance is superb. Great depth of field, black levels, and contrast.
Maybe there's a 48-1000 in my future...