Difficult to find Behringer documentation...

Behringer resets
note: SL2442FX /SL3242FX and SX2442FX/SX3242FX fx units test/reset by depressing both fx selection knobs while turning unit on

C-2 electret condenser microphone
schematic [newer releases incorporate suggested mods]

ECM8000 measurement microphone
response curve
also available in detail on download site for room eq wizard

EP2500 amplifier
intermittent distortion in either channel caused by dirty bias or current limit potentiometers [vr4 thru vr6 channel 1, vr1 thru vr3 channel 2]
voltage at pin 4 ic4 [channel 1] or ic6 [channel 2] would drop from -15vdc to -9vdc

mark trim settings as backup to resistance method below
measure resistance from wiper to ccw terminal of potentiometer [~ 1.07xx - 1.08xx k ohms vr1 , vr2, vr4, vr5, ~ 0.96xx ohms vr3, vr6; dmm required]
remove red sealing lacquer
inject methyl hydrate or other control cleaner into potentiometers and rotate trims to clean wiper tracks
reset trim to resistance measured above
verify trim settings approximate as marked above

check cable linking amplifier boards with ohm meter for intermittent connections [if intermittent flexing while powered disconnects part of the driver circuitry for the left board and may blow the 25a fuse]

SL2442FX mixer
block diagram
several forums cited input failure with different Behringer mixers
experienced failure as both intermittent [normal function restored after briefly overdriven] and persistent [normal function not restored]

i. externally - exercise lo cut, main, sub 1-2, sub 3-4 switches [also cause of failure to only left or right pan]
- remove level knob [simply pulls off] and inject .2cc methyl hydrate or other control cleaner at the level shaft/case opening while rotating shaft
ii. internally - white substance under the surface mount input pre-amp transistors located at the top edge of the input circuit board(s) possibly biases off those transistors
clean and repetitively rince with lacquer thinner or other solvent which dissolves substance without affecting surface mount components
subsequently similar rincing of the underside of the input circuit board(s) was required for some inputs
- [notes:
resoldering pre-amp section did not resolve failure
experienced failure of 4580 op amp once tested by voltage > 0.1vdc at pins 1 and 7]

block diagram