So, it appears that the reverb drive circuit is toast.
Seeing as the amp 'sounds like it has a blown speaker', I would rectify that before the reverb.
For now, I would disable the reverb circuit.
Remove TR 4 & Tr 5.
Lift one end of R30 & R29.
FYI: your voltage chart has the emitter & collector voltages inverted.

Can you post a pic of the jacks?

Although there are about 6 different G100 schematics, all of them basically take the speaker output & resistor the signal down for the record out.
To be specific please advise the exact model amp.

These should be clearer.

here is the complete schematic.

Use the scope on the output pins of each IC in the boost circuit.
Go down the line, left to right.

The radio tuning capacitor is the variable when it comes to 'selecting' a station frequency.
https://www.youtube.com/watch?v=5mE6v94zJ-A&t=1s

Personally, I don't think a 5332 op amp is going to drastically change the amp sound.
I would recommend NOT replacing the IC's as board damage is a given.
The traces are paper thin.
If you really want to change the dynamics of the amp , look at a better speaker.

Yeah, it is a bummer when the plated through hole comes out.
As G1 stated, running a small wire up through the hole is best for a good mechanical connection.

Usually the diodes & resistors for the mosfets get changed out as a matter of course.
(D39/40, R99/100)
Along with the gate driver ic (IRS20957S).
Unfortunately, that ic is out of production.
The only source is China.

Nice fix.

It appears to be a mute circuit.

Try it with Q4 removed.

Narrow it down.
Do any other controls affect the noise?
If so, then the issue is before that control.
An audio probe would help immensely.

Follow the noise backwards from the Master control.