They're all pushbutton switches, and I have (at least twice) cleaned the contacts with Deoxit.? It helped with some flaky behavior on the voltage ranges but did nothing for Ohms.? The upper 4 ohms ranges read garbage before I replaced Q11; now they at least are somewhat consistent, though way too high.? U3 actually measures good voltages at all the marked locations; but despite that, the gates of Q15 read different values.? The manual suggests shorting C1 and then checking gate voltages - it didn't make any difference.? I haven't changed the pot settings since replacing Q11, but I will go back in and measure the test points again before proceeding. If necessary I'll pull the pots and measure them.
The divider resistors R52-56 all measure proper values; you can force the switches to "all open" which essentially takes them all out of circuit and makes measurements possible without removing them.
I checked DCV on the 1V range, and it reads 0.03 whether open or short.? So, 30mV?? That seems quite a bit too high.
I'll take another look at some of the test points today and report back if anything changed markedly after swapping Q11.
