I remember some poor guy rewiring some of those core memory boards the last place I worked. Was told the piece of equipment it went into had no replacement available. What a hoot!
Yah, after the module was replaced, we attempted to fix the old one in the shop. Wow - that was tiny, intricate work. We did get it to work (without a proper micro-soldering station no less) but we sent it back to depot anyway, as the mission-critical nature of the equipment wouldn’t allow us to trust our home-made efforts. Bet it would’ve worked though…
So glad you started this thread, Jim. Brings back some memories of the good ol’ days…God, am I really old enough to say that? - Jeeesh!
ya know I used to think the beads in those core memory arrays were small… until I started designing boards with 0402 and (god forbid) 0201 parts on them. Just un-believable where stuff has gone in even the last 30 years.
0201 
if you drop that sucker, you will never find it. Heck, the nozzle must be supper small!