I found these grain of wheat bulbs from Electronic Goldmine to be the best match in the CS80:
https://www.goldmine-elec-products.com/prodinfo.asp?number=G15581These are smaller diameter than the original, but the voltage matches just right. If you have some original bulbs still working, you won't be able to see any difference in brightness.
Just center them in the little rubber clips and they work perfectly.