Distortion may be caused by your output tube grid going positive and drawing too much current. Check grid #1 voltage in relation to cathode on this tube. Grid #1 must remain a few volts negative. The exact voltage depends on tube type. It should never be positive. Since you already replaced caps it could be grid resistor open or output tube being gassy.
The replaced electroltyics should be ok. It takes time to replace these caps. This gives your radio time to cool, starting the cycle over again.
Norm
: Two Questions: One, have you got a schematic for a Lang model 613, circa 1956? Second, I need a little help tracking down repeating filter cap failure in that set. I read 80 and 120 volts on one or the other, tubes all test good, no shorts, all tubular caps replaced (twice), resistors that are marked are within value. Yet, after about an hour audio distortion gradually sets in, which is only resolved by puting in new electrolytics. I've even put in slightly larger values and greatly larger voltage ratings. Can you suggest anything? Thanks