@tautech, I sent you a PM. I talked to scott today beside trying to trace a signal through the front end with no schematics a 1052 mobo is about my only option.
Got it, been out all day.
I see little reason why if you dismantle the scope, then reconnect all cabling, why you couldn't trace the probe Cal squarewave in the broken channel with the good going one. Be sure to disconnect the Reference (Gnd) of the probe you use and place the sleeve on that covers the reference ring near the point.
This will test your detective work, but before you get ahead of yourself, first identify the active components in the channel input. Datasheets can save your bacon, they often have typical circuit examples and in this case the IC's used are likely scope input specific. This will give you little snapshots of the schematic, most likely enough to give clear points where you can test the signal path. While this might not point to the exact fault, it will narrow the fault to a smaller section, at which point you may be able to find a single faulty component.
Now for any in-circuit passive measurements, grab the pic I posted before of the input section and edit it pointing to any components and I'll measure them on the Mobo I have.
Good luck.
BTW, a very careful inspection of all the solder joints would be what I did first.