MVS 4 Slot sound on only slot 1 and 3 not 2 and 4

[cruzlink2]

Got a 4 slot from a friend that was not working, I patched a trace under the battery and got it to boot. Only issue is I get sound out of only slot 1 and 3 but not slot 2 and 4. I already cleaned the slots and inspected the board for for broken traces and found none aside the one under the battery.

 

[cruzlink2]

Some pictures.

 

[ItsBobDudes]

I know you said you cleaned the slots, but did you hit them with something like contact cleaner ?

 

[cruzlink2]

I know you said you cleaned the slots, but did you hit them with something like contact cleaner ?

Yep

 

[Neo-Alec]

Swap around the games and reset the backup ram.

 

[cruzlink2]

Swap around the games and reset the backup ram.

I did that and cleared the backup ram too same result, I feel like maybe one of the 74LS245Ps is out.