[morzh]

Bumping up the first cap will also increase your B+ voltage. See how much it is and if it is still within specs (the tubes will run hotter still).

Another thing to try could be using a 0.15uF or so cap in parallel with the filter choke (100V-rated will do) that is between the pluses of the 1st and 2nd electrolytic caps. You can variate the value, see if that helps. (seems counter-intuitive but it does help sometimes).

Could it be that when you restored the radio you simply did not hear the hum that was there, since it was (and is) low?
Could you possibly run it via Variac at 110V and now you are running it directly from MAINs at 120V?
There may be many things that were simply overlooked at the time of shelving it which now you pay attention to.