HP27 Restoration (Lots of Corrosion)

[calc-calcs]

Here are some fresh waveform shots, including the very crucial SYNC line which I had not checked before, but seems very odd. Notice the difference in level of that line as well (had to change that channel from 5V/div to 1V/div to see more detail), aside from the spiky shape.

Can anyone please confirm what is to be expected at the SYNC line of the HP27 ACT pin 20? Or if what is shown on the screenshots bellow is correct for that line?
Since the HP21 does not use a SYNC line could not make a direct comparison.

I also seem to have mixed up the ISA line in my previous scope shots, in these ones is the correct waveform which seems to make more sense.

The last shot also includes the DATA line, as seen while the display was blank. Tried to cycle power to get a reading with something on the display, but gave up after numerous tries ending with same blank screen.