There was a guy that I contacted a few years back. He takes the radio and get them working again. The bad news is, he no longer is doing this service. It was quite expensive anyways. I chose not to send mine in. My radio was working, i just had no way of checking the cassette tape. But he made them look & work like new again. I opted to put a new radio in, they are retro looking, but have the ability to hook your iPod up to them. Its just an option to consider, if your radio is toast.
https://www.retromanufacturing.com/p...k-series-truck