Hi Tim,
Further to the links provided by Steve pointing you to my valve portable set Success Stories, and in addition to what others have said I would suggest you also examine very closely the pins of all the valve sockets, especially that of the DL96.
It may not seem at all obvious but one or more broken pins making poor or intermittent contact may be the source of the 'weirdness' in your set rather than component failure. Especially as you say touching the DL96 grid pin produces a burst of operation.
The sockets used in these types of set are often prone to pin fatigue failure where one of the fork prongs breaks. They often look OK visually, but inserting a needle in each pin in turn will reveal which forks are broken and need replacing.
Its something you may not be too familiar with if your usual restorations are on mains sets rather than battery valve portables. I've found it can lead to some very strange problems!
Regards
