TBH I suspect the most useful resource for that would be a semiconductor cross-reference, because the SEM-1A schematic on the Internet Archive has a lot of obso

TBH I suspect the most useful resource for that would be a semiconductor cross-reference, because the SEM-1A schematic on the Internet Archive has a lot of obsolete parts: * the "standard NPN" (2N5172) is mostly discontinued; a few places have them for ~$1 apiece * the "standard FET" (2N4302) is very discontinued; SynthCube has a few NOS parts for $5(!) apiece * the CA3080 OTA is so discontinued that the first reissue by Rochester has also been discontinued; Alfa has cloned it as the AS3030E but compatibility is not 100% guaranteed. Some of these are overlapping - for instance, many of the FETs are used as buffers because the CA3080 has a weak output - but resolving them will practically be redesigning the circuit from scratch...