Guys, this is part of the issue I am asking about in my other thread...

1- user manual (Hifiengine has many online) for OEM part value.

2- eBay, Amazon, Zoro, Grainger, lots of sources.

2 major manufacturers of automotive and audio fuses (generally 1x1/4” or 5x25mm although 20mm length are also common) include Buss and Littelfuse.

3- fast or slow-blow are available in glass or ceramic packages.

4- as mentioned previously, power supply fuses are usually of more robust slow-blow, audio/speaker side of the fast-blow variety.

5- for some examples: https://www.littelfuse.com/products/fuses/cartridge-fuses.aspx

6- always have spares. This almost guarantees you’ll never need one.

also, find a few for sale on hifishark, perhaps someone here, write and ask if they have the manual with the spec,

or, original owner, never changed fuse, if they would look and see what fuses they have in there..

Search ebay for 3AG fuses.

Too much chance of a substandard device.
The fuse is the first line of defense for the amp and speakers

Digikey, Grainger, Mouser, McMaster-Carr
Fuse Manufacturers | Littlefuse, Bussmann, Mersen (fusesunlimited.com)

The extra couple of bux for shipping if you can't buy local is cheap insurance. Buy the exact required fuse. If it goes, there is a problem with the amp. Get it fixed.

In more than ½ century in HiFi, I've never replaced a fuse for failure.
Several because a manufacturer scrimped and installed no name crap.

As normb said, if you have a spare, you'll likely never need it.

Luckily for me I am the original owner of the amplifier so I don't have to worry about someone else previously changing the fuses to something incorrect. Sadly, one of the many benefits of the Internet Age was NOT helping the smaller, local shops. We had a great family chain here in Dallas that lasted decades.

Now, what you mostly see in brick and mortar stores are "Home Theater Studios" who aren't particularly interested in anything you have to say just how much you're willing to shell out $$$ in the hope your Media Room sounds and looks like an XD 3D theater.