[captainclock1988]

Hi, I'm wondering if your radio isn't a rebadged Sparton 1068 like the one seen in this thread here that was done by one of our fellow members Buzz.

If so, maybe try taking a look at the Sparton Schematic and see what's what there.

Also my Solid State Pioneer SX-1000 TD does a similar thing to your radio where it wants to motorboat if the Bass and Treble are turned all the way up, but works fine when its set to "flat" setting (where the Bass and Treble Controls are set to the middle) and the weird thing is that with my Pioneer it only does it in the AM Band Setting, all the other Settings work fine, except when it is in the middle of motorboating  and you switch it between the different band and input settings then the radio will continue to motorboat until you turn down the tone controls or turn off the radio and turn it back on again, but with my stereo its definitely tied with the tone controls (which in the Pioneer SX-1000 its the Control Amplifier Stage).

I hope this helps.

-Levi