[Amps] 3-500z - intermittent filament

[terry at g4amt.com]

My TL922 is mis-behaving with one tube operating intermittently. Symptoms 
were of open circuit filament but valve tested ok with ohm-meter and worked 
when refitted. Next power up, tube failed to work. jump soldered link wire 
to pins across bases to rule out base connections. Tube worked when pin and 
base `encouraged` with screwdriver.
Looks as though previous owner has attempted to resolder the filament pins 
and I suspect a dry joint (?) within one or both filament pins.
Is it safe to re-solder the pins ? Anything else suspicious I should be 
looking for ?

Many thanks

Terry