Marantz 2270 low freq roll off on one channel

[Jelcke]

Hello,
I am working on a 2270. I recapped the Power supply and replaced output transistors on R-ch.
After checking freq response I get low frequency roll off 20-300Hz on one channel.
The issue is already in the pre-amp output so I recapped the tone control board (400) and still no improvement.
Could someone please point me in the right direction?

schematic: http://akdatabase.org/AKview/displayimage.php?album=1&pos=103

 

[rcs16]

I find it strange that you know how to operate an Audio Precision test instrument but not a signal generator and a scope to troubleshoot your issue?

 

[Jelcke]

Well, it's true that I am a electronics novice with very nice gear.
I can operate a scope and signal generator but I would like to get some pointers on where to start looking. There are some parts in the amp that are hard to reach with a probe.. Like the P600 board. Contains high /low filters. but can't probe this board. (to deep into the amp)
What is the mosts probable cause for these kind of issues... caps?
thanks,
Jelcke

 

[EastPoint]

Did you clean all the controls with deoxit and work them back and forth a ton?

 

[Jelcke]

Cleaning all the buttons solved the problem. Thanks! Lesson learned.