Cannonshop is right. Terra probably is suffering from a rescource crunch. But does it suffer from a salvage crunch? Lots of raw materials remain it's just the process of converting it into something usable. There is also the issue of gathering raw materials from the belt and Mars and possibly other planets in the solar system. The amount of time needed for transport though may have made that untenable. The last thing I remember was the mech junkyards we see in the very first Dark Age novel. If nothing else they should have emptied those areas out for parts and materials.
You're thinking logically in straight lines with this, but that's not how people in the BT universe think. (or the real world, for that matter).
to fully grasp the problems here, consider a few things:
1. Belters
should have jumpships of their own for internal traffic, but they don't because that creates problems for the writers, so they have slowboats instead.
2. Recycling isn't always the answer (I know, heresy, right?) separating alloys out into their constituent elements is
insanely difficult, and may actually be more expensive than mining for the stuff in the raw and processing it from ore. It's also logistics and resource intensive to set up, and if you've already cut your economic throat with Gray Monday, followed by warfare, followed by Fortress? could well be that by the time someone crunched the numbers and did the math, it was too late to set it up. You also get losses because no system is truly perfect and you WILL have material loss, possibly of critical elements, even if you can shred and resmelt in the right proportions.
3. It's probable that those outer system sources are either too difficult to extract due to lack of infrastructure, or got tapped out. There's actually an extinct
MINERAL or two, if your industrial processes were optimized to use that mineral, and it runs out? you've got to re-tool if you want to keep running. Further, out-system sources will tend to be light minerals and elements. For heavies in off-earth operations inside sol system, you'd need to look a lot closer to the sun-since that's where the heavy elements accumulated. Mining the shade side of Mercury only works if it's stationary, and the conditions are...extreme. If you didn't invest in it during the time when more comfortable sources were available, it's going to be exceedingly costly to invest in the research when you're in a national crisis and have cut off all external ties, flatlined your communication grid, and are using your merchant fleet to bolster a wall.
while having tens of billions of empty stomachs to fill, most of whom don't have the necessary skills or psychology to work that sort of operation.
IOW, Devlin Stone laid the foundations of the Republic's demise and the ilClan's rise long before he left office for the first time-about the time he started planning his cryochamber vacation, you might say, or setting up Gray monday's outage, and in the process of that, he also set up Terra to fall to the Clans, because of a lack of investment in technologies that would make his fortress defensible once the walls came down. He simply didn't consider losing, and assumed a few years of blackout would allow the Republic to freely conquer in any direction against enemies that had expended their forces on one another. (this is actually mentioned in Pardoe's novel)