Okay, that is likely because the emitter resistors are acting the way intended and saving the output transistors.
We need to find out why the Bias is not adjusting down.
Going on past experience with these amplifiers, we need to look at all the traces on the circuit board associated with the trimmer, you need to make sure, the trimmer is making connection via the tracks to where its supposed to joined to.
The tracks on these circuit boards, and the F2980 in particular are very very fragile, they can look fine, but the crack and get hairline cracks around the solder pads. So you need to verify that the trimmer is working in circuit.
You can do this with your multimeter, look at the circuit and then Ω it out...
Also, do you have any freeze spray? You could hit the STV3 Diode on the heatsink and see if the bias current changes, it will go up.
If you have no freeze spray you could hold the soldering on the STV3 and the Bias current will go down.
This will verify the STV, these are not normally a failure point, but there is a first time for everything.