larryderouin is correct in all particulars... the 2SC458s are used for gain with low-noise, but unfortunately that transistor type did not age well-- even within 5-10 years they needed replacement, apparently, according to folks who were service techs in the 70s and 80s, because they became noisy... ironic for a device initially chosen for low-noise qualities. I believe there were a couple in the STEREO indicator circuit as well, but as noise there isn't in the audio signal path the replacement there is perhaps not as crucial.
KSC1845s are a great replacement, and there are indeed about ten of them between those three circuit sections, and a couple more scattered about in the non-audio path as I imply above. I am not sure whether I should have used KSC1815 instead in some of those positions-- looks to me like the primary difference is in how much current is required for the application: 1845s are 120V, lower current and 1815s are 60V, higher current, and I will be the first to admit my understanding of how to analyze a circuit to determine what would work better there is pathetic at best.
You've come to the right place. The 2000 is a well-understood piece of equipment around these parts.
