[PaulR]

Thank you for the thoughts. This was a general question prompted by replacing the two caps in the Philips which is actually an AC/DC radio. The hum is not bad at all but is discernible at the low volumes I use as a bed side radio. It has an iffy valve holder and so will probably need looking at again before long and I might experiment with the negative connection of the reservoir capacitor then.

I usually find that the smoothing caps on 50s and later sets reform quite well. I connect them to a variable HT power supply with an ammeter in line and slowly crank up the voltage over several hours as the current decreases. This is the first time I have had one fail after several year's use and it made me think about the negative lead connections as the most convenient places for the replacements are not where the original was. I used to restuff electrolytics for this reason but cannot really be bothered now.

Something to think about for future restorations - if I can ever squeeze another set into the house past my wife!!