6 amp, fast blow for the internal rail fuses. For example, Bussman AGC-6, Littelfuse 312008, or similar. Common and inexpensive--any hardware store or auto parts store should have these.
Rear panel fuse for 120-volt operation will be a 12A, slow blow. Bussman MDA-12 or Littelfuse 326012 should work. The MDA and 326 series are ceramic, probably expensive and hard-to-find. MDL-12 or 313012 glass fuses do not have the voltage capacity, don't use those.
