Saw that SIP package on the dodgy heatsink, and, aside from diodes on the power board, the transformer pins being dry jointed and that SIP package has the only thing holding it to the board being a single screw at one end ( applied after the wave soldering) and knew that one or more of those pins are dry. Mostly because the holes are larger than you expect from the lead dimensions.
Then off to the QC team, who plugged it in to a chassis jig, and aligned it, after doing the visual inspection and adding of "production line enhancements" to the board. Then off to assembly, where, because Sony wanted them to need almost no after assembly adjustment, they probably worked perfectly on test.
Got an Aiwa unit of similar function, made around 1988, and it still is in use daily, though sadly the LCD displays have started to darken from age, the CD player requires yet another KSS210 laser assembly, and while it is only 11 pounds on eBay, I actually have not listened to a CD in years. Tape deck ( the fancy dual deck with high speed dubbing) the same, all the rubber parts and a good number of plastic bits are broken, so it is a very nice FM radio now, with a built in clock and the ability to have timed turn on.
When the CD player actually worked, in the 1990's, I used it to wake to music, so wanted the CD player to start playing on power on, which it did not do. So, added one CD4016 CMOS analogue switch, and a few cascaded RC circuits, to simply wait 10 seconds after power on, and emulate pressing play for a half second. Fitted on a bit of Veroboard 8 strips by 6 holes, and used what I could find around, lots of Vishay wet tantalums and similar (never seen them again, but have a box of mixed ones) dry rectangular tantalum capacitors, which used colour dots for value and voltage on the black surface, like old style mica capacitors and resistors, and polarity was marked by the one lead being gold, and the other being silver.