Aiwa AD F990 - how can I source the dolby IC / Chip

[nikhilblr]

Hi Everybody a few years back I had purchased an Aiwa ADF 990 cassette deck which I restored around 6 or seven months back where I replaced all the idlers and belts with brand new ones. Unfortunately after getting it back in working condition it was observed that the left channel has distortion and the technician who repaired it said that the Dolby chip / IC for that Channel needs to be replaced. While I've tried searching for the Dolby IC online on eBay and various other places I haven't actually managed to find one yet. Is there any other fix that someone can think of which is completely out of the box where we bypass the dolby IC completely. I'm not really an electronics expert so I don't know much about this but if anybody has any good suggestions please let me know. I've tried to find chips from other Aiwa models in the series like ADF 770 etc. as well but no luck.