[Arran]

The first thing I would try on weak testing 01As is to resolder the pins, especially if they are the older balloon types. Sometimes you will need to remove the bases to do this which involves melting the old putty with lacquer thinner to get them off, and then windshield adhesive to glue them back on, but try touching them up first to see if there is an improvement. The solder they used in the 1920s was not the best, and it gets worse with age. I've actually thought about making a test adapter involving a four or five pin base with alligator clip leads for testing early tubes with the base off, I'm running into flaky solder joints a lot with things like #24s and #26s. Nothing is guaranteed though, it may only work on some of the tubes or none at all, but until we can convince someone overseas to make new 01As you sometimes have to make do.
Regards
Arran