[morzh]

Replacing shields...

the word "replace" has at least two meaning:

1. Put something bakc where it was taken from.
2. Put something instead of something else.

Which one do you mean? if #1, yes, very well could result in noise.
If #2...rarely work, if ever. However, the very act of disturbing the shields sometimes helps as they develop oxidation and sometimes are not grounded. An especially popular problem with aluminum shields flared to a chassis. So cleaning the places where the shields meet the chassis and then making sure there is a good solid contact there (with an Ohmmeter) might help.

[Arran]

Matt;
Some battery sets had an electrolytic filter cap in the B+ line, and if those fail you can end up with a hum no matter how good the battery eliminator is. They were typically of a small value, but rated at 150 VDC, this Philco does not have one of those, so the hum may be caused by a tube shield being left off. It also appears to have a number of large bypass caps contained inside a can under the chassis, they will need to be replaced eventually if you intend to use the set regularly.
Regards
Arran