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I have a similar Silvertone roundie. Mine is very much like a ctc15. Mine had a problem that required the coil to be misadjusted to achieve lock. The natural frequency of the oscillator was wrong.
The procedure goes something like this, as I recall. There is a sync test point (look on sams) that you can ground to disable all sync. You then short out the sinewave coil (that would be the upper half of the horiz oscillator coil, the one with the movable slug).
WIth the sync and sinewave coil disabled, you adjust horizontal hold for a picture that is right side up (though probably pretty unstable). Now the natural frequency is correct. My set would not do this, the "right side up" place was off one end of the horizontal hold control.
If you could get this part right, you would then remove the short from the sinewave coil and adjust the sinewave coil for a picture right side up again. What you have done is made it so the sinewave coil adds stability, without changing the natural frequency. You then remove the short from the sync test point, and the set returns to normal operation.
I couldnt get past the first part. The natural frequency was way off, and needed a misadjustment of the sinewave coil to pull it back on.
The culprit turned out to be an .0015 dip mylar capacitor that couples the horizontal oscillator to the horizontal output stage. It had gone up in value.
Here are some other possibilities: The capacitor that mainly determines the natural frequency is a 390pf 2kv ceramic disc, I think. There is also a suspicious looking 680pf polyprop in a funky cardboard shield. RCA usually used mica here I think. My polyprop was fine. It also couldnt hurt to check the resistors on each side of the horizontal hold control.
Good Luck,
John
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