kicker kx850.4 one channel has lower output then the other 3

[ivkata]

happy holidays to all
thank you for taking the time to check my listing .I just took this amp as a trade in from the original owner ,the issue was that one of the channels has lower output than the other 3.the bad channel has clean output its just allot quieter that the other 3 -i would say 10 watts tops .operating the switches in all ranges and using other source and rca cable dosent change anything .please advise

[Perry Babin]

I don't have anything on that amp but similar amps have 1 or 2 muting transistors for each channel. They typically have the lowest circuit board designations for the channel. Find the muting transistor(s) for the weak channel. Compare the audio level on the muting transistors in the other channels. If the the audio is weaker on the weak channel, remove the muting transistors to see if that makes a difference.