[Heathkit] VFO tubes for 104A VFO needed

[John King via Heathkit]

My grandson's Heath 104A transceiver has a couple of nixie tubes in the VFO display out. They are heath part number 411-295 which is a SP-352 display tube. Does anyone know of a source for these display tubes. If so please advise me of the source. He is KG5EOV, Morgan, a high school freshman. I want to help him get the display working. He has it pumping out its' rated output in watts thanks to the gracious assistance of Mike Bryce, WB8VGE of the Heathkit Shop.
I am trying to encourage him in the excitement of Amateur Radio. I could have GIVEN him one of my several operational transceivers but I felt that the experience and thrill of accomplishment might offset his infatuation with IPODS and Computers. Thanks for any input. 73, John, K5PGW