Earlier I took measurements to see if I could find any shorted pins.
I made a few errors due to not realizing pins 21-24 weren't in sequential order with the SEG lines, so I measured DP2 to SEG-E (by way of measuring the VFD pins directly) thinking the pins on the IC were next to each other.. By the time I realized this error, it was late and had to call it a day.
From the measurements I took, none of the pins were shorted, however, one odd thing I noticed was SEG-COM wasn't connected to ground (unless I'm wrong, I've been using chassis ground as it appears ground is connected to chassis ground).
Maybe SEG-COM is floating, but thought to mention it.
After measuring for shorts, I powered the unit and took scope measurements (see attached - file names are according to which pin was measured). Upon powering it, I checked the heatsink (again) and it was fairly cool. After keeping the unit powered for about fifteen-minutes (the longest I've kept it powered since the display stopped working) while taking scope measurements, I turned off the unit and touched the heatsink. This time it burned the back of my index finger; believe this indicates something is wrong.
The 5v measures about 4.8v I believe, however, whichever the voltage is falls within the range in the service manual.
Update: I didn't think to include my next step(s). Looking at the schematic tells me possibly one of the two capacitors are bad, however, looking at the board, I don't see an electrolytic; nor do I see the same components on the board as the schematic.
I'll check the resistance to ground before the diode, but it's looking like I may need to remove the VFD again.