famicom sound way off inquiry

[chessimprov]

I had an acquaintance tell me it was okay to use rubbing alcohol and that I couldn't use too much to affect the cartridges or the system.  I'm wondering if I did or if maybe the wires got unhooked or something, because when I play games on my famicom now, the sound is god awful.  It happened on a video game event at someone's place.  At first we thought maybe the guy's TV was getting old, but then the same thing happened on my end.  There was nothing wrong with it beforehand.  

I know my adapter and video cables are not an issue more than likely, as they worked perfectly fine on a super famicom.

This famicom was not used in over 10 years, then it was time to take it out since another old one was losing its productivity.  Any thoughts?  Thank you very much.

[80sFREAK]

If you want help, you have to be more specific.

[chessimprov]

I'm a total rookie at this.  I'm not sure how to be more specific.  some questions could help, but if I can't get more help, I understand enough. Thank you for taking a look!

[80sFREAK]

Ok, i think i know, what is the problem.... You need philips screwdriver, eraser, cotton stick and some pure alcohol. Open controller II, there is slider, rub it gently with eraser, clean after with cotton stick dipped in alcohol. Clean with cotton stick "rails" on PCB, where slider suppose to slide. Assemble it back.

[chessimprov]

I found out from a repair shop (this one's far away from me, but it's worth it when I head up that way) that the sound chip is cracked.  Not sure how something could crack in a few months unless someone dropped the machine.  Temperature is another possibility, but haven't had any extremes here during that period.

Any other possible causes out there?

Also, apparently the famicom is a third party clone.  So, the repair shop was not able to determine what sound chip I should get.  I don't even know if it would be worth it for me to buy some random sound chip or not.  I don't have or want to spend the money on a new famicom system since this one just replaced another one about 10+ years old.