if the orig filter caps are still in, then there is a good chance they are leaky dragging the B+ down. The B+ readings help in this regard but there are other things that can drag down the B+
the cans are only near signal tubes, it would take a while to radiate enough heat from them, so it is quite possible you have a problem there.
there is also a rather large decoupling cap off the vert out primary, while not part of the power supply it certainly can be an issue.
If the B+ is suspect you should check the filter cans with a proper old school cap tester. If you do not have one of those its prob wiser to just go ahead and restuff them.
this is the method I recommend.
https://www.youtube.com/watch?v=kh2yurjt5sM
they maybe ok, but without the correct tester its hard to tell. If the B+ is ok (the 382v and the 270v) then they are prob ok.
I just like to find the problem and replace the part as needed rather than shot gunning. You learn more that way.
the method in the video is good since it leaves all the wire dress alone as well as the parts that are often soldered directly to the can terminals.
I can do a 4 section can in prob 10min. others use term strips but the prob there is if its done wrong it just makes it harder for the next guy to figure it out. Same with tacking caps in various places, yes it can work but its hard to follow IF it does not work.