Sony Fh-5 low sound

[SkinnyDonut]

Hi, I am facing a problem with this Sony amplifier system. A little back story!

Found it half a year ago in my Attic and I have tried it to make it work since. I had no output whatsoever i did, but recently i found the problem! It was the headphone connector partially disconnected and because it's connected in series with the speaker terminals it didn't produced any sound

Now the problem is that the volume is really low
Can anyone guide me to the right direction?

 

[Superduper]

It probably needs to be cleaned really well with solvent to remove oxidation from the internal contacts which could be making a poor connection. Also not just that, if it's been in your attic for God knows how long, many of the switches could be oxidized.

 

[SkinnyDonut]

It probably needs to be cleaned really well with solvent to remove oxidation from the internal contacts which could be making a poor connection. Also not just that, if it's been in your attic for God knows how long, many of the switches could be oxidized.

After testing I found out that one channel has oversaturated and clipping sound and the other channel has oversaturated sound as well but low volume