The Nichicon VTs (which I numbered 1, 7 and 8) are reporting a higher ESR than I'd expect (2.05, 1.53 and 1.89 respectively). I've tested all 13 electrolytics with an inline ESR meter, and there are some notable results.
I've never seen a three legged cap before but I do have a Vishay datasheet for the 678D series, so I've at least got something to work off. They're Sprague 678D caps but with three legs. One thing which has me scratching my head is the caps that I marked as 10 and 11. Also a CSV of the caps and what values they are. Here's a photo of the two boards, with the caps numbered for reference. There's no electrolytics on the motherboard itself, they're all confined to two PSU boards - the AC adapter and a secondary one in the laptop itself.
Due to the age of the system, I suspected that the electrolytic capacitors are drying out. It sounds to me like there's not enough power being provided to spin up the hard disk.
I powered it off to prevent it from possibly getting damaged further. At the stage of the POST where it would normally spin up the hard disk, I could hear the drive starting to spin up, but then it rebooted again and spun down the disk. This time, I had it on for a few hours when it spontaneously rebooted itself and the hard disk spun down. After the memory test, it spins up the hard disk. When you power it up, it goes through the POST sequence and performs a memory test. Also, it recently did something it never did before. I don't know how long exactly, but it would be within 15 minutes. On some occasions when you power it down, it won't come back up until you unplug it from the PSU and let it sit for a while. But recently it began showing some signs of what I suspect are capacitor issues. Up to now, the only bit of physical maintenance I had to do was to replace the Dallas DS1287 RTC with a DS12887 to replace the CMOS battery. Useless by modern standards but it's an oddity I like to keep running it's certainly a head turner when anyone sees it! I have a very old Compaq SLT/286 laptop which I keep alive as a hobby of mine.
I best start off by saying that I've zero recapping experience, although I do have some casual experience with soldering and desoldering components.
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