I think I found a photo of the board, and it looks like C93 might be connected to Q2, which on the photo I've found is marked RIA or R1A, which could be an NPN transistor or a small adjustable voltage reference. If it's an NPN transistor then it might be used to connect the outer pin of C93 to Ground. If true, then it's not directly connected to the main ground, so that's ok that you didn't find a connection. Worth checking that there's no short between centre and outer pins. I wonder if it's part of the keylock control, it's near J10 which I think is the keylock header. I'm slightly surprised there's no connection to one of the power supplies from the centre pin and wonder what it's connected to.
If you follow Deunan's advice and test for shorts on the J7 power connector then I guess you'll find pin 4 (-12V) shorted to ground. Looking at the traces near the J7 power connector, it looks like -12V goes to one of the outer pins of C100, and the centre pin goes to Ground. If that's right, then that means there's a short from -12V to Ground somewhere (so all C100 pins connect to ground). If that's true, then C100 is also centre +ve (-12V -> Ground, probably true for C111 as well).
I think that then leaves just C114 as the odd one out. All the others look to be centre +ve. Would you mind double checking the measurements for that one, once you've cleared any shorts?
The capacitor values look odd. From your earlier information then C113 is rated for 25V, but is used between +5V and Ground. But C101 was only rated for 16V and was used between +12V and Ground. I really would have expected those values to be the other way around. As Deunan said, 25V is better on the +/-12V lines.
Oh, last odd thing, on your first measurements you listed C84 as shorted, and now it's listed as connected to 5V. Did something change with that one?