Greg,
Some American tubes require a cap value of 5pf while others need
10pf. The original value of C-120 is 100pf. A better idea is to switch
your rig over to 8950 tubes. These tubes are easier to find, work much
more efficiently, with a slight power increase over stock and it is an
easy mod. The entire mod is covered in the FOX/TANGO newsletters!
Tom KC�NSC