When I've lost that fuse (about 3 times now) it has often been the result of grounding something behind the dash (where I spend far too much time anyway).

The cabin fan usually dies with that fuse and the AMP light comes on.

You can get new fuses from www.SwedishTreasures.com for around $2.00 each. I usually order a couple whenever I get anything from them. Trouble is, that I think you need a paypal account to order from them...

I am all too familiar with the artistic cash flow issues. My father was a master caligrapher, but perpetually poor. He could hardly keep his car licensed even before insurance was required nor could he afford simple mechanical upkeep. My 1972 145 died in his care and was sent to the junkyard for a little cash. I'm continually nagged by the thought that I could have probably fixed that 140 if we had the BrickBoard back then... I should have saved the HIF6 carbs at the very least..

As suggested, you can bypass the top fuse if you pick up an in-line blade fuse holder and some crimp-on alligator clips and clip it to each side of the fusebox. It's not a permanent solution, but it's a handy thing to keep around in case you loose that fuse again. I keep one in a little altoid tin along with my spare fuses

I've been told that a careful hand and a pair of piers can re-bend that particular connector to accept a modern 25 amp fuse. I've never tried myself.

If you can't hunt any correct fuses up, I, or another Brickboard member could send you one ASAP.