Hi everybody,
I did some searching for the replacement fuse used in high voltage in Admiral tv's and others to protect the flyback. The old Bussmann part number is F01GR250A and the new number AGX-1/4. The 1/4 is the amps. Mouser has these fuses and their part number is 504-AGX-1/4. They are $2.02 for up to 9 fuses and then the price drops to $1.62 for 10 - 50 fuses. I thought I would share this info if anybody needs these fuses.

AGX fuses are the old 8AG fuses - 1" in length, and originally made for instrument protection. Electronics Surplus has the 1/4 Ampere fuses (http://www.electronicsurplus.com/littelfuse-361-25-fuse-1-4amp-250vac-package-of-5)at $3 for 5 fuses, a lot cheaper than the Mouser Bussmann ones. Littelfuse makes 8AG in two "speeds" - the 361.250 (8AG, 1/4A) is the fastest, and the 362 being just "fast." Either would probably do for flyback protection/cathode current fusing.
We used the 1/4 Amp ones in some old Weston meters in the Navy, and ordered the Littelfuse ones over the MIL F01 series - a LOT cheaper, and at the time, available locally from two electronics places.

Cheers,