I know this sounds like a stupid question, but why are you installing a CB? If its to add to the looks of the Amity blazer, then you probably need to try to find something close to the movie.
But, if you are actually going to be using it a lot, then its probably best to just go with a new one.
In looking around, I see they are not as cheap as they used to be when I was so heavily involved in them, but you can probably get a new one for what it would take to fix that one.
Even back in the day, I would often just get a new one when one of mine died. Unless it was a special one.
For instance, I rebuilt the Pace 223 several times over the years. But it would key about 8 watts right out of the box, and only took one transistor and one adjustment to get almost 50 out of it.
Not that I would do anything like that of course........
If the radios were stock, and/or hard to work on, I would do some basic checks, like loose solder joints, bad mic or antenna, and it was going to take some serious bench work, I would just chunk it and get another.
If yours is actually new out of the box, its probably something simple to fix, but by the time we shipped it here, I found time to work on it, and shipped it back, you could have a new one up and running for not much more than the shipping costs.
I would not charge for working on it of course, but with the move to the swamp coming up along with other stuff, I don't know when I would have time to work on it.
I wish you were closer, I would love to look it over. Not sure if I could fix it at this late date though.
I gave away all my schematics and manual years ago. Heck, even some of my equipment is gone.
Some given away, some lost when friends died who I had loaned it to.
Got any good flea markets around your area? I used to see them in those all the time at good prices.