I think that fuse is purely for the feed to the iPod dock. Clearly, that must have been giving problems too. I had to have the main internal fuse replaced (under guarantee - it was 10 years ago!) which is an internal, circuit board mounted and directly soldered, mains fuse protecting the main unit (mine is an AD88 but the circuitry is the same as the F80). It looks like a small terracotta coloured cylinder with the rating on its cylindrical surface and the two connecting wires protruding from its bottom surface. As has been remarked, they changed the rating and my unit is always in standby or powered on and it has lasted 10 years so far - though I have no need to play the unit at high volumes.

Cinema/Music: Trinnov Altitude32 8-16,218,Cloud 4 channel, Marantz UD5007,DSP5200SE(2+C),DSP3300(4),DSW(2),271,MShort Ceilings,AppleTV 4K
TV: Marantz SR7013 Wharfedale Diamond 9x4+Celestion(C)
Music: Roon,i7NUC8gen,QNAP TS253A, Sony Scala, MS200, Garrard DDQ650,Wharfedale Diamond 12.3
Kitchen: AD88 (bluetooth via i80).