Otari Mx 5050 tape machine STILL wont switch from 2 track to 4 track. Tips?

Hi there! This tape machine switches from 4 to 2 track. There’s a slider switch on the head stack. I’ve cleaned that switch with Electrical Contact Cleaner but it does not make it switch to 4 track.

I’m playing commercial tapes that are 4 track, so I hear the correct music, plus music playing backwards at the same time.

And tips for what to look for on the circuit board? I can solder, but I’m slow at reading schematics and tracing voltages.
 
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Yup, I fixed one broken trace on the circuit board for the switch and now it works.

Thanks, AnalogApples, you’re the best!

EDIT: I don’t know what I was thinking saying this is fixed, it’s not.
 
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Glad to hear you fixed it! I had a lot of "fun" repairing a D550 synthesizer with a cracked PCB on the control panel recently. Needed about 9 jump wires to bypass the damage, but it works nicely now.
 
So, actually the problem was that the switch was dirty. Interestingly enough, electrical contact cleaner did not fix it, but Caig Deoxit did fix it. I’m writing this to help other weary travelers in Otari land
 
Hello, could you pls put the picture of the switch , where it is located ?
May vary depending on the version. According to one of the manuals it's on the back of the head cover - but I can see on some other machines, you have to lift up the head cover and it'll be near the back.

Either way, the heads are connected to a PCB at the back of the head block, and the switch will be mounted on that.
 
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