if the fuse itself is ok, chances are there is a problem with the fusebox itself...easy way to find out is to do a resistence check between the blower switch plug wire to the fuse..
can do a temp test of the switch/motor etc by just running a 12v feed to the 12v live wire on back of switch and turn the blower on.
if that works, then
what they mean by looping is to run a bridge wire between either a spare 12v feed from the fuse box, or any spare 12v supply, bearing in mind you need to connect to similar size/amp wire as the 12v on back of switch..fit a sufficient amp fuse within that bridge.
new fuseboxes are expensive, but they are repairable, though time consuming and fiddly,
if you opt for a s/hand fuse box, you need to make sure they are the same as there were many different versions of them, plus your problem was fairly common so might end up no better off.
problems are normally down to corrosion/poor contacts within the box, if its only affecting one circuit [as they often did} then a bridge wire is the quickest and cheapest way round the problem, just take care everything is fused and insulated correctly and its perfectly safe