I use this fuse.
Took copper caps from a cheaper fuse, took the ones on this off, refilled cylinder with carbon based Heatsink paste (Arctic mx-5), put new endcaps back on with epoxy glue.
The cheaper fuse I sourced for parts is the Aucharm fuse from aliexpress, goes for about $2.
Resolution and distortion are miles ahead of the stock Gustard fuse.