Af9 maxon auto filter not working

[9 volts]

Hi there, I'm trying to troubleshoot my af9 auto filter. (Like a mutron). It is working well when the drive button is switched to up but when switched to down the sound remains very thin and doesn't wha. Also the the range hi low switch doesn't seem to have any effect. I have checked the switches and they are working. I figured that since the layout looks similar to the mutron/neutron, someone may be able to help me troubleshoot. Thanks

[GibsonGM]

Well, without a schematic and some more info, it's not really feasible to give much advice, 9. 

Did YOU build it, or buy it factory-made?   How long ago?

Did it used to work ok?  If so, odds are good that the switch is somehow messed up...loose solder connections due to mechanical stress, or a screwed up part inside of it.   

Next step would be to take it out of its case or otherwise gain access to the board.