Originally Posted by
guitar_gazza
After I replaced it with the fuse stated in the manual and the same as the one that came out of the amp, a F1.6A, the amp powered up but it blew again shortly afterwards. I found that I had a faulty power tube. I replaced both power tubes, 6L6 tubes and replaced the fuse again and BINGO, that was the problem. The amp is now running fine with a fast blow fuse and new power tubes.
The thing is, I have a friend with a couple of vintage Fenders and they both have SLO blow fuses, so Fender must have changed somewhere along the line with the fuses they use.