You can also try using #1847 bulbs instead. They are basically a beefier #47.
If you can stomach the price, there are some nice GE ones on eBay:
ebay.com link: GE NOS 47 1847 bulb brass bases longlife version of 47 lamps box of 10
Also, Pinsider tomdrum had some NOS ones a while back. Might check with him for a cheaper price than eBay.