No drive select on Frontman 25r

[Roly]

Yeah, I have no strong opinion here except that something doesn't fit, and I've always found it profitable to follow the bit that doesn't fit.

E.g. to take JM's thought that the real fault here may actually be a cracked track, not a boofed FET, and that this has only been incidentally "fixed" in the process of replacing Q2.

On one hand the symptoms as reported pointed to Q2; but now, on the other hand, we have replacing Q1 as an effective repair, and I'm at a loss to see how the initial reported fault of "stuck in crunch" could be caused by a fault at Q1 if the switching rail at the join of the 1Meg and two diodes was actually going to -6.5V. 

I suspect there is another boot yet to hit the floor here.   

[buffalocomputer]

I did not see any cold joints or cracked traces before replacing the transistors, but I did not try to reflow the joints either. I did fully test after replacing Q1 and got the same results. I will try to find time tonight to get some post-repair voltage readings for comparison. Any suggested test points would be appreciated

[J M Fahey]

The right side (as on schematic, may point anywhere on the actual PCB) of the 1M shows alternating +/-6.5V ,you already measured that.
Follow the track and check that you find the same voltage on each diode caathode.
Then measure on each diode anode.
You should find there the negative voltage (when present), but not the positive one (a properly working diode will not let it through)
Last but not least, check that you get the negative voltage (when approppriate) at the FET leg itself.
Measure both the solder pad and the actual FET leg on component side, in case there is an unseen crack.
And believe me that sometimes I *know* they are there but can't see them even with a jeweler's loupe and under good light.